Advances in GBA-associated Parkinson's disease--Pathology, presentation and therapies

Molecular mechanisms of the ambroxol action in Gaucher disease and GBA1 mutation-associated Parkinson disease

Glucocerebrosidase (GCase), encoded by the GBA1 gene, is one of the lysosomal enzymes responsible for hydrolyzing the glycosphingolipids. Deficiency in GCase activity (in patients with two defective alleles of GBA1) leads to glucosylceramide storage in lysosomes which in turn results in the development of the Gaucher diseases, a lysosomal storage disorder, while a heterozygous state may be correlated with the GBA1 mutation-associated Parkinson disease. One of the proposed forms of therapy for these two conditions is the use of pharmacological chaperones which work by facilitating the achievement of the correct conformation of abnormally folded enzymes. Several compounds with chaperone activities against GCase have already been tested, one of which turned out to be ambroxol. Studies conducted on the action of this compound have indeed indicated its effectiveness in increasing GCase levels and activity. However, some data have begun to question its activity as a chaperone against certain GCase variants. Then, a number of articles appeared pointing to other mechanisms of action of ambroxol, which may also contribute to the improvement of patients' condition. This paper summarizes the biological mechanisms of action of ambroxol in Gaucher disease and GBA1 mutation-associated Parkinson disease, focused on its activity as a chaperone, modulator of ERAD pathways, inducer of autophagy, and pain reliever in cellular and animal models as well as in patients. The effects of these activities on the reduction of disease markers and symptoms in patients are also discussed. Consideration of all the properties of ambroxol can help in the appropriate choice of therapy and the determination of the effective drug dose.

Prediction of Parkinson's disease pathogenic variants using hybrid Machine learning systems and radiomic features

PURPOSE

In Parkinson's disease (PD), 5-10% of cases are of genetic origin with mutations identified in several genes such as leucine-rich repeat kinase 2 (LRRK2) and glucocerebrosidase (GBA). We aim to predict these two gene mutations using hybrid machine learning systems (HMLS), via imaging and non-imaging data, with the long-term goal to predict conversion to active disease.

METHODS

We studied 264 and 129 patients with known LRRK2 and GBA mutations status from PPMI database. Each dataset includes 513 features such as clinical features (CFs), conventional imaging features (CIFs) and radiomic features (RFs) extracted from DAT-SPECT images. Features, normalized by Z-score, were univariately analyzed for statistical significance by the t-test and chi-square test, adjusted by Benjamini-Hochberg correction. Multiple HMLSs, including 11 features extraction (FEA) or 10 features selection algorithms (FSA) linked with 21 classifiers were utilized. We also employed Ensemble Voting (EV) to classify the genes.

RESULTS

For prediction of LRRK2 mutation status, a number of HMLSs resulted in accuracies of 0.98 ± 0.02 and 1.00 in 5-fold cross-validation (80% out of total data points) and external testing (remaining 20%), respectively. For predicting GBA mutation status, multiple HMLSs resulted in high accuracies of 0.90 ± 0.08 and 0.96 in 5-fold cross-validation and external testing, respectively. We additionally showed that SPECT-based RFs added value to the specific prediction of of GBA mutation status.

CONCLUSION

We demonstrated that combining medical information with SPECT-based imaging features, and optimal utilization of HMLS can produce excellent prediction of the mutations status in PD patients.

Lipid profiles in the cerebrospinal fluid of rats with 6-hydroxydopamine-induced lesions as a model of Parkinson's disease

Background

Parkinson's disease (PD) is a progressive neurodegenerative disease with characteristic pathological abnormalities, including the loss of dopaminergic (DA) neurons, a dopamine-depleted striatum, and microglial activation. Lipid accumulation exhibits a close relationship with these pathologies in PD.

Methods

Here, 6-hydroxydopamine (6-OHDA) was used to construct a rat model of PD, and the lipid profile in cerebrospinal fluid (CSF) obtained from model rats was analyzed using lipidomic approaches.

Results

Establishment of this PD model was confirmed by apomorphine-induced rotation behaviors, loss of DA neurons, depletion of dopamine in the striatum, and microglial activation after 6-OHDA-induced lesion generation. Unsupervised and supervised methods were employed for lipid analysis. A total of 172 lipid species were identified in CSF and subsequently classified into 18 lipid families. Lipid families, including eicosanoids, triglyceride (TG), cholesterol ester (CE), and free fatty acid (FFA), and 11 lipid species exhibited significantly altered profiles 2 weeks after 6-OHDA administration, and significant changes in eicosanoids, TG, CE, CAR, and three lipid species were noted 5 weeks after 6-OHDA administration. During the period of 6-OHDA-induced lesion formation, the lipid families and species showed concentration fluctuations related to the recovery of behavior and nigrostriatal abnormalities. Correlation analysis showed that the levels of eicosanoids, CE, TG families, and TG (16:0_20:0_18:1) exhibited positive relationships with apomorphine-induced rotation behaviors and negative relationships with tyrosine hydroxylase (TH) expression in the midbrain.

Conclusion

These results revealed that non-progressive nigrostriatal degeneration induced by 6-OHDA promotes the expression of an impairment-related lipidomic signature in CSF, and the level of eicosanoids, CE, TG families, and TG (16:0_20:0_18:1) in CSF may reveal pathological changes in the midbrain after 6-OHDA insult.

What to Test in Parkinson Disease Prevention Trials? Repurposed, Low-Risk, and Gene-Targeted Drugs

Despite the sound epidemiologic and basic science rationales underpinning numerous "disease modification" trials in manifest Parkinson disease (PD), none has convincingly demonstrated that a treatment slows progression. Rapidly expanding knowledge of the genetic determinants and prodromal features of PD now allows realistic planning of prevention trials with initiation of putatively neuroprotective therapies earlier in the disease. In this article, we outline the principles of drug selection for PD prevention trials, focused on proof-of-concept opportunities that will help establish a methodological foundation for this fledgling field. We describe prototypical, relatively low-risk drug candidates for such trials (e.g., albuterol, ambroxol, caffeine, ibuprofen), tailored to specific at-risk populations ranging from pathogenic LRRK2 or GBA gene variant carriers to those defined by prodromal PD and α-synucleinopathy. Finally, we review gene-targeted approaches currently in development targeting clinically manifest PD for their potential in future prevention trials.

Epigallocatechin Gallate (EGCG) for Parkinson's Disease

In the last couple of decades, we have experienced increased use of nutraceuticals worldwide with a demand for organic foods, which has been elevated to an extent probably unmatched with other periods of our civilization. One of the nutraceuticals that gained attention is epigallocatechin gallate (EGCG), a polyphenol in green tea. It has been suggested that diseases of the central nervous system (CNS) can benefit from consuming some antioxidants, despite current results showing little evidence for their use in preventing and treating these diseases. ECGC may be beneficial in delaying the neurodegeneration of the substantia nigra (SN) regardless of the origin of Parkinson's disease (PD). This review covers the effect of EGCG on vitro and animal models of PD, the potential mechanisms of neuroprotection involved and summaries recent clinical trials in human PD. This review also aims to provide an investigative analysis of the current knowledge in this field and identify putative crucial issues. Environmental factors such as dietary habits, drug use, and social interaction are all factors that influence the evolution of neurodegenerative diseases. Therefore, the use of nutraceuticals requires further investigation. This article is protected by copyright. All rights reserved.

Emerging Therapeutic Strategies for Parkinson’s Disease and Future Prospects: A 2021 Update

Parkinson’s disease (PD) is a neurodegenerative disorder pathologically distinguished by degeneration of dopaminergic neurons in the substantia nigra pars compacta. Muscle rigidity, tremor, and bradykinesia are all clinical motor hallmarks of PD. Several pathways have been implicated in PD etiology, including mitochondrial dysfunction, impaired protein clearance, and neuroinflammation, but how these factors interact remains incompletely understood. Although many breakthroughs in PD therapy have been accomplished, there is currently no cure for PD, only trials to alleviate the related motor symptoms. To reduce or stop the clinical progression and mobility impairment, a disease-modifying approach that can directly target the etiology rather than offering symptomatic alleviation remains a major unmet clinical need in the management of PD. In this review, we briefly introduce current treatments and pathophysiology of PD. In addition, we address the novel innovative therapeutic targets for PD therapy, including α-synuclein, autophagy, neurodegeneration, neuroinflammation, and others. Several immunomodulatory approaches and stem cell research currently in clinical trials with PD patients are also discussed. Moreover, preclinical studies and clinical trials evaluating the efficacy of novel and repurposed therapeutic agents and their pragmatic applications with encouraging outcomes are summarized. Finally, molecular biomarkers under active investigation are presented as potentially valuable tools for early PD diagnosis.

Bioengineered models of Parkinson's disease using patient-derived dopaminergic neurons exhibit distinct biological profiles in a 3D microenvironment

Three-dimensional (3D) in vitro culture systems using human induced pluripotent stem cells (hiPSCs) are useful tools to model neurodegenerative disease biology in physiologically relevant microenvironments. Though many successful biomaterials-based 3D model systems have been established for other neurogenerative diseases, such as Alzheimer's disease, relatively few exist for Parkinson's disease (PD) research. We employed tissue engineering approaches to construct a 3D silk scaffold-based platform for the culture of hiPSC-dopaminergic (DA) neurons derived from healthy individuals and PD patients harboring LRRK2 G2019S or GBA N370S mutations. We then compared results from protein, gene expression, and metabolic analyses obtained from two-dimensional (2D) and 3D culture systems. The 3D platform enabled the formation of dense dopamine neuronal network architectures and developed biological profiles both similar and distinct from 2D culture systems in healthy and PD disease lines. PD cultures developed in 3D platforms showed elevated levels of α-synuclein and alterations in purine metabolite profiles. Furthermore, computational network analysis of transcriptomic networks nominated several novel molecular interactions occurring in neurons from patients with mutations in LRRK2 and GBA. We conclude that the brain-like 3D system presented here is a realistic platform to interrogate molecular mechanisms underlying PD biology.

The contribution of CNVs to the most common aging-related neurodegenerative diseases

Alzheimer and Parkinson's diseases are neurodegenerative aging-related pathological conditions, mainly caused by the interplay of genetic and non-genetic factors and whose incidence rate is going to drastically increase given the growing life expectancy. To address these complex multifactorial traits, a systems biology strategy is needed to highlight genotype-phenotype correlations as well as overlapping gene signatures. Copy number variants (CNVs) are structural chromosomal imbalances that can have pathogenic nature causing or contributing to the disease onset or progression. Moreover, neurons affected by CNVs have been found to decline in number depending on age in healthy controls and may be selectively vulnerable to aging-related cell-death. In this review, we aim to update the reader on the role of these variations in the pathogenesis of Alzheimer and Parkinson diseases. To widen the comprehension of pathogenic mechanisms underlying them, we discuss variations detected from blood or brain specimens, as well as overlapped signatures between the two pathologies.

Aerts J, Moratalla R. The Role of Cholesterol in α-Synuclein and Lewy Body Pathology in GBA1 Parkinson's Disease

Parkinson's disease (PD) is a progressive neurodegenerative disease where dopaminergic neurons in the substantia nigra are lost, resulting in a decrease in striatal dopamine and, consequently, motor control. Dopaminergic degeneration is associated with the appearance of Lewy bodies, which contain membrane structures and proteins, including α-synuclein (α-Syn), in surviving neurons. PD displays a multifactorial pathology and develops from interactions between multiple elements, such as age, environmental conditions, and genetics. Mutations in the GBA1 gene represent one of the major genetic risk factors for PD. This gene encodes an essential lysosomal enzyme called β-glucocerebrosidase (GCase), which is responsible for degrading the glycolipid glucocerebroside into glucose and ceramide. GCase can generate glucosylated cholesterol via transglucosylation and can also degrade the sterol glucoside. Although the molecular mechanisms that predispose an individual to neurodegeneration remain unknown, the role of cholesterol in PD pathology deserves consideration. Disturbed cellular cholesterol metabolism, as reflected by accumulation of lysosomal cholesterol in GBA1-associated PD cellular models, could contribute to changes in lipid rafts, which are necessary for synaptic localization and vesicle cycling and modulation of synaptic integrity. α-Syn has been implicated in the regulation of neuronal cholesterol, and cholesterol facilitates interactions between α-Syn oligomers. In this review, we integrate the results of previous studies and describe the cholesterol landscape in cellular homeostasis and neuronal function. We discuss its implication in α-Syn and Lewy body pathophysiological mechanisms underlying PD, focusing on the role of GCase and cholesterol. © 2020 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Towards physiologically relevant human pluripotent stem cell (hPSC) models of Parkinson's disease

The derivation of human embryonic stem cells followed by the discovery of induced pluripotent stem cells and leaps in genome editing approaches have continuously fueled enthusiasm for the development of new models of neurodegenerative diseases such as Parkinson's disease (PD). PD is characterized by the relative selective loss of dopaminergic neurons (DNs) in specific areas of substantia nigra pars compacta (SNpc). While degeneration in late stages can be widespread, there is stereotypic early degeneration of these uniquely vulnerable neurons. Various causes of selective vulnerability have been investigated but much remains unclear. Most studies have sought to identify cell autonomous properties of the most vulnerable neurons. However, recent findings from genetic studies and model systems have added to our understanding of non-cell autonomous contributions including regional-specific neuro-immune interactions with astrocytes, resident or damage-activated microglia, neuro-glia cell metabolic interactions, involvement of endothelial cells, and damage to the vascular system. All of these contribute to specific vulnerability and, along with aging and environmental factors, might be integrated in a complex stressor-threshold model of neurodegeneration. In this forward-looking review, we synthesize recent advances in the field of PD modeling using human pluripotent stem cells, with an emphasis on organoid and complex co-culture models of the nigrostriatal niche, with emerging CRISPR applications to edit or perturb expression of causal PD genes and associated risk factors, such as GBA, to understand the impact of these genes on relevant phenotypes.

Association of gender and age at onset with glucocerebrosidase associated Parkinson's disease: a systematic review and meta-analysis

Glucocerebrosidase (GBA) gene has been proved to be a risk factor for the development of Parkinson's disease (PD). However, the gender effect in the prevalence of GBA-associated PD (GBA-PD) is still controversial. And there is no conclusion whether the age at onset (AAO) of PD is different between carriers and non-carriers of GBA. To clarify the association between gender and AAO in GBA-PD, we conducted a systematic review and meta-analysis. PubMed, Web of Science, and Embase were retrieved to obtain potentially related studies. The odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to determine the association between gender and GBA-PD. And the weighted mean difference (WMD) with 95% CIs was employed to assess the difference of AAO between carriers and non-carriers of GBA. A total of twenty-eight studies involving 16,488 PD patients were included in this meta-analysis. The results showed the prevalence of female patients was higher in GBA-PD [OR: 1.19, (95% CI, 1.07-1.32), P = 0.001]. Meanwhile, GBA carriers had younger age at PD onset than GBA non-carriers [WMD: 2.87, (95% CI, 2.48-3.27), P < 0.001]. Results of subgroup analysis showed the prevalence of women in GBA-PD was higher than men in North American and European PD patients, while the gender difference was not significant in other areas around the world, suggesting an ethnic specificity of gender effect for GBA-PD. Our results indicate the higher female prevalence with ethnic specificity and younger AAO of GBA carriers in GBA-PD.

Identification of GBA mutations among neurodegenerative disease patients from eastern India

INTRODUCTION

GBA mutations have been reported in PD, PDD and DLB - but not associated with cognitive impairment for example in PSP, AD or MSA. However, frequencies of GBA mutations are ethnicity dependent. The present study aims to identify commonly reported GBA mutations (mostly from Asia), among eastern Indian patients with neurodegenerative disorders.

METHODS

The patient cohort consisting of 198 classical PD cases, 136 PD cases with cognitive impairment, 184 cases with Parkinson Plus syndrome, 46 AD and 241 unrelated controls, from eastern India. Subjects were analyzed for IVS2 + 1A > G, p.Arg120Trp, p.His255Gln, p.Arg257Gln, p.Glu326Lys, p.Asn370Ser, p.Asp409His, p.Leu444Pro, & RecNciI by PCR-RFLP techniques and confirmed by Sanger sequencing method.

RESULTS

We have identified only p.Leu444Pro variant among nine cases; three PDD, one DLB, two PD, two PSP and one AD patients in heterozygous condition. The highest frequency for p.Leu444Pro variant was found among PDD subgroup (3.95 %, P = 0.0134). An overall significant overrepresentation of positive family history (P = 0.000049), impaired recent memory (P = 0.0123) was observed among p.Leu444Pro carriers. Further, subgroup analysis for PD, PD-MCI and PDD, revealed statistically significant higher frequency of early age at onset (P = 0.0455), positive family history (P = 0.0025), higher UPDRS III score (off state) (P = 0.006), advanced H&Y stage (P = 0.045) and anxious behaviour (P = 0.0124) among p.Leu444Pro positive patients.

CONCLUSION

The p.Leu444Pro mutation of GBA was found in patients with PD, PDD, DLB, PSP and AD. An Overall higher frequency of positive family history and impaired recent memory are significantly associated with for p.Leu444Pro carriers from eastern India. Our study also ascertains contribution of p.Leu444Pro to an earlier onset of PD, PD-MCI and PDD, higher UPDRS III score (off state) against positive family history background. Furthermore, taking into consideration other Indian studies, we can conclude that p.Leu444Pro mutation plays a limited role in PD and other neurodegenerative disorders.

Synaptic Function and Dysfunction in Lysosomal Storage Diseases

Lysosomal storage diseases (LSDs) with neurological involvement are inherited genetic diseases of the metabolism characterized by lysosomal dysfunction and the accumulation of undegraded substrates altering glial and neuronal function. Often, patients with neurological manifestations present with damage to the gray and white matter and irreversible neuronal decline. The use of animal models of LSDs has greatly facilitated studying and identifying potential mechanisms of neuronal dysfunction, including alterations in availability and function of synaptic proteins, modifications of membrane structure, deficits in docking, exocytosis, recycling of synaptic vesicles, and inflammation-mediated remodeling of synapses. Although some extrapolations from findings in adult-onset conditions such as Alzheimer's disease or Parkinson's disease have been reported, the pathogenetic mechanisms underpinning cognitive deficits in LSDs are still largely unclear. Without being fully inclusive, the goal of this mini-review is to present a discussion on possible mechanisms leading to synaptic dysfunction in LSDs.

Advancing Personalized Medicine in Common Forms of Parkinson's Disease through Genetics: Current Therapeutics and the Future of Individualized Management

Parkinson’s disease (PD) is a condition with heterogeneous clinical manifestations that vary in age at onset, rate of progression, disease course, severity, motor and non-motor symptoms, and a variable response to antiparkinsonian drugs. It is considered that there are multiple PD etiological subtypes, some of which could be predicted by genetics. The characterization and prediction of these distinct molecular entities provides a growing opportunity to use individualized management and personalized therapies. Dissecting the genetic architecture of PD is a critical step in identifying therapeutic targets, and genetics represents a step forward to sub-categorize and predict PD risk and progression. A better understanding and separation of genetic subtypes has immediate implications in clinical trial design by unraveling the different flavors of clinical presentation and development. Personalized medicine is a nascent area of research and represents a paramount challenge in the treatment and cure of PD. This manuscript summarizes the current state of precision medicine in the PD field and discusses how genetics has become the engine to gain insights into disease during our constant effort to develop potential etiological based interventions.

GBA Mutations Influence the Release and Pathological Effects of Small Extracellular Vesicles from Fibroblasts of Patients with Parkinson's Disease

Heterozygous mutations in the GBA gene, encoding the lysosomal enzyme glucocerebrosidase (GCase), are the strongest known genetic risk factor for Parkinson's disease (PD). The molecular mechanisms underlying the increased PD risk and the variable phenotypes observed in carriers of different GBA mutations are not yet fully elucidated. Extracellular vesicles (EVs) have gained increasing importance in neurodegenerative diseases since they can vehiculate pathological molecules potentially promoting disease propagation. Accumulating evidence showed that perturbations of the endosomal-lysosomal pathway can affect EV release and composition. Here, we investigate the impact of GCase deficiency on EV release and their effect in recipient cells. EVs were purified by ultracentrifugation from the supernatant of fibroblast cell lines derived from PD patients with or without GBA mutations and quantified by nanoparticle tracking analysis. SH-SY5Y cells over-expressing alpha-synuclein (α-syn) were used to assess the ability of patient-derived small EVs to affect α-syn expression. We observed that defective GCase activity promotes the release of EVs, independently of mutation severity. Moreover, small EVs released from PD fibroblasts carrying severe mutations increased the intra-cellular levels of phosphorylated α-syn. In summary, our work shows that the dysregulation of small EV trafficking and alpha-synuclein mishandling may play a role in GBA-associated PD.

Mitophagy, a Form of Selective Autophagy, Plays an Essential Role in Mitochondrial Dynamics of Parkinson's Disease

Parkinson's disease (PD) is a severe neurodegenerative disorder caused by the progressive loss of dopaminergic neurons in the substantia nigra and affects millions of people. Currently, mitochondrial dysfunction is considered as a central role in the pathogenesis of both sporadic and familial forms of PD. Mitophagy, a process that selectively targets damaged or redundant mitochondria to the lysosome for elimination via the autophagy devices, is crucial in preserving mitochondrial health. So far, aberrant mitophagy has been observed in the postmortem of PD patients and genetic or toxin-induced models of PD. Except for mitochondrial dysfunction, mitophagy is involved in regulating several other PD-related pathological mechanisms as well, e.g., oxidative stress and calcium imbalance. So far, the mitophagy mechanisms induced by PD-related proteins, PINK1 and Parkin, have been studied widely, and several other PD-associated genes, e.g., DJ-1, LRRK2, and alpha-synuclein, have been discovered to participate in the regulation of mitophagy as well, which further strengthens the link between mitophagy and PD. Thus, in this view, we reviewed mitophagy pathways in belief and discussed the interactions between mitophagy and several PD's pathological mechanisms and how PD-related genes modulate the mitophagy process.

The Emerging Role of the Lysosome in Parkinson's Disease

Lysosomal function has a central role in maintaining neuronal homeostasis, and, accordingly, lysosomal dysfunction has been linked to neurodegeneration and particularly to Parkinson’s disease (PD). Lysosomes are the converging step where the substrates delivered by autophagy and endocytosis are degraded in order to recycle their primary components to rebuild new macromolecules. Genetic studies have revealed the important link between the lysosomal function and PD; several of the autosomal dominant and recessive genes associated with PD as well as several genetic risk factors encode for lysosomal, autophagic, and endosomal proteins. Mutations in these PD-associated genes can cause lysosomal dysfunction, and since α-synuclein degradation is mostly lysosomal-dependent, among other consequences, lysosomal impairment can affect α-synuclein turnover, contributing to increase its intracellular levels and therefore promoting its accumulation and aggregation. Recent studies have also highlighted the bidirectional link between Parkinson’s disease and lysosomal storage diseases (LSD); evidence includes the presence of α-synuclein inclusions in the brain regions of patients with LSD and the identification of several lysosomal genes involved in LSD as genetic risk factors to develop PD.

Emerging Targeted Therapeutics for Genetic Subtypes of Parkinsonism

In recent years, a precision medicine approach, which customizes medical treatments based on patients' individual profiles and incorporates variability in genes, the environment, and lifestyle, has transformed medical care in numerous medical fields, most notably oncology. Applying a similar approach to Parkinson's disease (PD) may promote the development of disease-modifying agents that could help slow progression or possibly even avert disease development in a subset of at-risk individuals. The urgent need for such trials partially stems from the negative results of clinical trials where interventions treat all PD patients as a single homogenous group. Here, we review the current obstacles towards the development of precision interventions in PD. We also review and discuss the clinical trials that target genetic forms of PD, i.e., GBA-associated and LRRK2-associated PD.

Characterization of a pathogenic variant in GBA for Parkinson's disease with mild cognitive impairment patients

Parkinson's disease (PD) is the second most common neurodegenerative disease, and mild cognitive impairment (MCI) is a well-established risk factor for the development of dementia in PD. A growing body of evidence suggests that low expression of glucocerebrosidase (GBA) promotes the transmission of α-synuclein (α-Syn) interpolymers and the progression of PD. However, how GBA mutations affect the pathogenesis of PD via abnormal aggregation of α-Syn is unclear, and no clinically valid PD-MCI genetic markers have been identified. Here, we first located a GBA eQTL, rs12411216, by analysing DHS, eQTL SNP, and transcription factor binding site data using the UCSC database. Subsequently, we found that rs12411216 was significantly associated with PD-MCI (P < 0.05) in 306 PD patients by genotyping. In exploring the relationship between rs12411216 and GBA expression, the SNP was found to be associated with GBA expression in 50 PD patients through qPCR verification. In a further CRISPR/Cas9-mediated genome editing module, the SNP was identified to cause a decrease in GBA expression, weaken enzymatic activity and enhance the abnormal aggregation of α-Syn in SH-SY5Y cells. Additionally, using an electrophoretic mobility shift assay, we confirmed that the binding efficiency of transcription factor E2F4 was affected by the rs12411216 SNP. In conclusion, our results showed that rs12411216 regulated GBA expression, supporting its potential role as a PD-MCI genetic biomarker and highlighting novel mechanisms underlying Parkinson's disease.

Direct Cost of Parkinson's Disease: A Real-World Data Study of Second-Line Therapies

Parkinson's disease is one of the main reasons for neurological consultation in Spain. Due to the nature of the disease, it impacts patients, families, and caregivers. Parkinson's disease is a degenerative disease with no cure, although second-line therapies have recently improved the quality of life of patients in advanced stages. The aim of this study was to analyse the costs of the following therapies: deep brain stimulation (DBS), continuous duodenal levodopa/carbidopa infusion (CDLCI), and continuous subcutaneous apomorphine infusion (CSAI). The methodology used was based on real-world data obtained from an integrated healthcare organization in the Basque Country from 2016 to 2018. This bottom-up retrospective approach only took into account the healthcare perspective. The results revealed the annual cost over 3 years and the projected cost for an additional 2 years. The total costs for 5 years of treatment were as follows: €53,217 for DBS, €208,163 for CDLCI, and €170,591 for CSAI. These costs are in line with those found in the available literature on the subject. Additionally, the analysis provided details of the different costs incurred during intervention with the therapies and compared the costs to those reported in other studies.

Modeling Parkinson's Disease Using Induced Pluripotent Stem Cells

Parkinson's disease (PD) is the second most common neurodegenerative disease. The molecular mechanisms of PD at the cellular level involve oxidative stress, mitochondrial dysfunction, autophagy, axonal transport, and neuroinflammation. Induced pluripotent stem cells (iPSCs) with patient-specific genetic background are capable of directed differentiation into dopaminergic neurons. Cell models based on iPSCs are powerful tools for studying the molecular mechanisms of PD. The iPSCs used for PD studies were mainly from patients carrying mutations in synuclein alpha (SNCA), leucine-rich repeat kinase 2 (LRRK2), PTEN-induced putative kinase 1 (PINK1), parkin RBR E3 ubiquitin protein ligase (PARK2), cytoplasmic protein sorting 35 (VPS35), and variants in glucosidase beta acid (GBA). In this review, we summarized the advances in molecular mechanisms of Parkinson's disease using iPSC models.

Neuropathophysiology of Lysosomal Storage Diseases: Synaptic Dysfunction as a Starting Point for Disease Progression

About two thirds of the patients affected with lysosomal storage diseases (LSD) experience neurological manifestations, such as developmental delay, seizures, or psychiatric problems. In order to develop efficient therapies, it is crucial to understand the neuropathophysiology underlying these symptoms. How exactly lysosomal storage affects biogenesis and function of neurons is still under investigation however recent research highlights a substantial role played by synaptic defects, such as alterations in synaptic spines, synaptic proteins, postsynaptic densities, and synaptic vesicles that might lead to functional impairments in synaptic transmission and neurodegeneration, finally culminating in massive neuronal death and manifestation of cognitive symptoms. Unveiling how the synaptic components are affected in neurological LSD will thus enable a better understanding of the complexity of disease progression as well as identify crucial targets of therapeutic relevance and optimal time windows for targeted intervention.

Are Glucosylceramide-Related Sphingolipids Involved in the Increased Risk for Cancer in Gaucher Disease Patients? Review and Hypotheses

The roles of ceramide and its catabolites, i.e., sphingosine and sphingosine 1-phosphate, in the development of malignancies and the response to anticancer regimens have been extensively described. Moreover, an abundant literature points to the effects of glucosylceramide synthase, the mammalian enzyme that converts ceramide to β-glucosylceramide, in protecting tumor cells from chemotherapy. Much less is known about the contribution of β-glucosylceramide and its breakdown products in cancer progression. In this chapter, we first review published and personal clinical observations that report on the increased risk of developing cancers in patients affected with Gaucher disease, an inborn disorder characterized by defective lysosomal degradation of β-glucosylceramide. The previously described mechanistic links between lysosomal β-glucosylceramidase, β-glucosylceramide and/or β-glucosylphingosine, and various hallmarks of cancer are reviewed. We further show that melanoma tumor growth is facilitated in a Gaucher disease mouse model. Finally, the potential roles of the β-glucosylceramidase protein and its lipidic substrates and/or downstream products are discussed.

Precision medicine in Parkinson's disease: emerging treatments for genetic Parkinson's disease

In recent years, numerous clinical trials for disease modification in Parkinson's disease (PD) have failed, possibly because of a "one-size-fits all" approach. Alternatively, a precision medicine approach, which customises treatments based on patients' individual genotype, may help reach disease modification. Here, we review clinical trials that target genetic forms of PD, i.e., GBA-associated and LRRK2-associated PD. In summary, six ongoing studies which explicitely recruit GBA-PD patients, and two studies which recruit LRRK2-PD patients, were identified. Available data on mechanisms of action, study design, and challenges of therapeutic trials are discussed.

Effects of glucocerebrosidase gene polymorphisms and mutations on the risk of Parkinson's disease dementia: A meta-analysis

OBJECTIVE

Exploring the impact of glucocerebrosidase gene (GBA) polymorphisms and mutations on the pathogenesis of Parkinson's disease dementia (PDD) plays an important role in the diagnosis and treatment of this disease. This meta-analysis aimed to investigate the effects of GBA polymorphisms and mutations on the risk of PDD and to identify the relationship between GBA genotype and PDD.

METHODS

A computer-based search was performed to retrieve publications from PubMed, Cochrane library, Embase, Chinese Biomedical Literature Database, China National Knowledge Infrastructure, and Wanfang databases using the search terms "glucocerebrosidase", "Parkinson's disease", and "dementia". After rigorous screening, cohort studies were included for meta-analysis.

RESULTS

The risk of PDD in GBA variant carriers was 1.94 times that in non-carriers (hazard ratio [HR], 1.94; 95% confidence interval [CI], 1.53-2.46). The risk of PDD in GBA polymorphism carriers was 1.87 times that in non-carriers (HR, 1.87; 95% CI, 1.18-2.98). The risk of PDD in GBA mutation carriers was 3.64 times that in non-carriers (HR, 3.64; 95% CI, 2.74-4.83). The risk of PDD in p.L444P variant carriers (HR, 4.81; 95% CI, 3.37-6.86) was significantly higher than that in p.N370S variant carriers (HR, 1.95; 95% CI, 1.29-1.94).

CONCLUSION

GBA polymorphisms and mutations are potential risk factors for PDD.

Glucocerebrosidase Activity Modulates Neuronal Susceptibility to Pathological α-Synuclein Insult

Mutations in the GBA1 gene are the most common genetic risk factor for Parkinson's disease (PD) and dementia with Lewy bodies (DLB). GBA1 encodes the lysosomal lipid hydrolase glucocerebrosidase (GCase), and its activity has been linked to accumulation of α-synuclein. The current study systematically examines the relationship between GCase activity and both pathogenic and non-pathogenic forms of α-synuclein in primary hippocampal, cortical, and midbrain neuron and astrocyte cultures, as well as in transgenic mice and a non-transgenic mouse model of PD. We find that reduced GCase activity does not result in aggregation of α-synuclein. However, in the context of extant misfolded α-synuclein, GCase activity modulates neuronal susceptibility to pathology. Furthermore, this modulation does not depend on neuron type but rather is driven by the level of pathological α-synuclein seeds. This study has implications for understanding how GBA1 mutations influence PD pathogenesis and provides a platform for testing novel therapeutics.

GBA, Gaucher Disease, and Parkinson's Disease: From Genetic to Clinic to New Therapeutic Approaches

Parkinson’s disease (PD) is the second most common degenerative disorder. Although the disease was described more than 200 years ago, its pathogenetic mechanisms have not yet been fully described. In recent years, the discovery of the association between mutations of the GBA gene (encoding for the lysosomal enzyme glucocerebrosidase) and PD facilitated a better understating of this disorder. GBA mutations are the most common genetic risk factor of the disease. However, mutations of this gene can be found in different phenotypes, such as Gaucher’s disease (GD), PD, dementia with Lewy bodies (DLB) and rapid eye movements (REM) sleep behavior disorders (RBDs). Understanding the pathogenic role of this mutation and its different manifestations is crucial for geneticists and scientists to guide their research and to select proper cohorts of patients. Moreover, knowing the implications of the GBA mutation in the context of PD and the other associated phenotypes is also important for clinicians to properly counsel their patients and to implement their care. With the present review we aim to describe the genetic, clinical, and therapeutic features related to the mutation of the GBA gene.

Immune system and new avenues in Parkinson’s disease research and treatment

Parkinson’s disease (PD) is a progressive neurological disorder characterized by degeneration of dopaminergic neurons in the substantia nigra. However, although 200 years have now passed since the primary clinical description of PD by James Parkinson, the etiology and mechanisms of neuronal loss in this disease are still not fully understood. In addition to genetic and environmental factors, activation of immunologic responses seems to have a crucial role in PD pathology. Intraneuronal accumulation of α-synuclein (α-Syn), as the main pathological hallmark of PD, potentially mediates initiation of the autoimmune and inflammatory events through, possibly, auto-reactive T cells. While current therapeutic regimens are mainly used to symptomatically suppress PD signs, application of the disease-modifying therapies including immunomodulatory strategies may slow down the progressive neurodegeneration process of PD. The aim of this review is to summarize knowledge regarding previous studies on the relationships between autoimmune reactions and PD pathology as well as to discuss current opportunities for immunomodulatory therapy.

Dysregulation of the autophagic-lysosomal pathway in Gaucher and Parkinson's disease

The finding that mutations in the Gaucher's Disease (GD) gene GBA1 are a strong risk factor for Parkinson's Disease (PD) has allowed for unique insights into pathophysiology centered on disruption of the autophagic-lysosomal pathway. Protein aggregations in the form of Lewy bodies and the effects of canonical PD mutations that converge on the lysosomal degradation system suggest that neurodegeneration in PD is mediated by dysregulation of protein homeostasis. The well-characterized clinical and pathological relationship between PD and the lysosomal storage disorder GD emphasizes the importance of dysregulated protein metabolism in neurodegeneration, and one intriguing piece of this relationship is a shared phenotype of autophagic-lysosomal dysfunction in both diseases. Translational application of these findings may be accelerated by the use of midbrain dopamine neuronal models derived from induced pluripotent stem cells (iPSCs) that recapitulate several pathological features of GD and PD. In this review, we discuss evidence linking autophagic dysfunction to the pathophysiology of GD and GBA1-linked parkinsonism and focus more specifically on studies performed recently in iPSC-derived neurons.

Parkinson's disease: Cause factors, measurable indicators, and early diagnosis

Parkinson's disease (PD) is a neurodegenerative disease of the central nervous system caused due to the loss of dopaminergic neurons. It is classified under movement disorder as patients with PD present with tremor, rigidity, postural changes, and a decrease in spontaneous movements. Comorbidities including anxiety, depression, fatigue, and sleep disorders are observed prior to the diagnosis of PD. Gene mutations, exposure to toxic substances, and aging are considered as the causative factors of PD even though its genesis is unknown. This paper reviews PD etiologies, progression, and in particular measurable indicators of PD such as neuroimaging and electrophysiology modalities. In addition to gene therapy, neuroprotective, pharmacological, and neural transplantation treatments, researchers are actively aiming at identifying biological markers of PD with the goal of early diagnosis. Neuroimaging modalities used together with advanced machine learning techniques offer a promising path for the early detection and intervention in PD patients.

Molecular regulations and therapeutic targets of Gaucher disease

Gaucher disease (GD) is the most common lysosomal storage disease caused by deficiency of beta-glucocerebrosidase (GCase) resulting in lysosomal accumulation of its glycolipid substrate glucosylceramide. The activity of GCase depends on many factors such as proper folding and lysosomal localization, which are influenced by mutations in GCase encoding gene, and regulated by various GCase-binding partners including Saposin C, progranulin and heat shock proteins. In addition, proinflammatory molecules also contribute to pathogenicity of GD. In this review, we summarize the molecules that are known to be important for the pathogenesis of GD, particularly those modulating GCase lysosomal appearance and activity. In addition, small molecules that inhibit inflammatory mediators, calcium ion channels and other factors associated with GD are also described. Discovery and characterization of novel molecules that impact GD are not only important for deciphering the pathogenic mechanisms of the disease, but they also provide new targets for drug development to treat the disease.

Modeling Parkinson's Disease in Drosophila: What Have We Learned for Dominant Traits?

Parkinson’s disease (PD) is recognized as the second most common neurodegenerative disorder after Alzheimer’s disease. Unfortunately, there is no cure or proven disease modifying therapy for PD. The recent discovery of a number of genes involved in both sporadic and familial forms of PD has enabled disease modeling in easily manipulable model systems. Various model systems have been developed to study the pathobiology of PD and provided tremendous insights into the molecular mechanisms underlying dopaminergic neurodegeneration. Among all the model systems, the power of Drosophila has revealed many genetic factors involved in the various pathways, and provided potential therapeutic targets. This review focuses on Drosophila models of PD, with emphasis on how Drosophila models have provided new insights into the mutations of dominant genes causing PD and what are the convergent mechanisms.

Glucocerebrosidase mutations and neuropsychiatric phenotypes in Parkinson's disease and Lewy body dementias: Review and meta-analyses

Heterozygous mutations in glucocerebrosidase gene (GBA) are a major genetic risk factor for Parkinson's disease (PD) and dementia with Lewy bodies (DLB). Recently, there has been a considerable focus on the relationship between GBA mutations and emergence of cognitive impairment and neuropsychiatric symptoms in these diseases. Here, we review the literature in this area, with a particular focus, including meta-analysis, on the key neuropsychiatric symptoms of cognitive impairment, psychosis, and depression in Parkinson's disease. Our meta-analysis demonstrated that GBA mutations are associated with a 2.4-fold increased risk of cognitive impairment. In addition, our novel meta-analyses of psychosis and depression showed a 1.8- and 2.2-fold increased risk respectively associated with GBA mutations, although due to possible bias and heterogeneity the depression findings should be interpreted with caution. While the precise mechanisms which increase susceptibility to neurodegeneration in GBA carriers are not known, evidence of greater cortical Lewy body pathology, reduced patterns of cortical activation, and hippocampal pathology in animal models are all consistent with a direct effect of GBA mutations on these symptoms. Extension of this work in DLB and individuals without neurodegeneration will be important in further characterizing how GBA mutations increase risk for PD and DLB and influence disease course.

Silencing of Glucocerebrosidase Gene in Drosophila Enhances the Aggregation of Parkinson's Disease Associated α-Synuclein Mutant A53T and Affects Locomotor Activity

Background: Mutations in glucocerebrosidase (GBA), a lysosomal enzyme are the most common genetic risk factor for developing Parkinson's disease (PD). We studied how reduced GCase activity affects α-synuclein (α-syn) and its mutants (A30P and A53T) aggregation, neurodegeneration, sleep and locomotor behavior in a fly model of PD.

Methods: We developed drosophila with GBA gene knockdown (RNAi) (with reduced GCase activity) that simultaneously expresses either wildtype (WT) or mutants such as A30P or A53T α-syn. Western blot and confocal microscopy were performed to study the α-syn aggregation and neurodegeneration in these flies. We also studied the sleep and locomotor activity of those flies using Drosophila activity monitor (DAM) system.

Results: Western blot analysis showed that GBA RNAi A53T α-syn flies (30 days old) had an increased level of Triton insoluble synuclein (that corresponds to α-syn aggregates) compared to corresponding A53T flies without GBA RNAi (control), while mRNA expression of α-syn remained unchanged. Confocal imaging of whole brain staining of 30 days old drosophila showed a statistically significant decrease in neuron numbers in PPL1 cluster in flies expressing α-syn WT, A30P and A53T in the presence GBA RNAi compared to corresponding control. Staining with conformation specific antibody for α-syn aggregates showed an increased number of neurons staining for α-syn aggregates in A53T fly brain with GBA RNAi compared to control A53T flies, thus confirming our protein analysis finding that under decreased GBA enzyme activity, mutant A53T aggregates more than the control A53T without GBA silencing. Sleep analysis revealed decreased total activity in GBA silenced flies expressing mutant A53T compared to both A53T control flies and GBA RNAi flies without synuclein expression.

Conclusion: In A53T flies with reduced GCase activity, there is increased α-syn aggregation and dopamine (DA) neuronal loss. This study demonstrates that reduced GCase activity both in the context of heterozygous GBA1 mutation associated with PD and in old age, contribute to increased aggregation of mutant α-syn A53T and exacerbates the phenotype in a fly model of PD.

Treatable inherited rare movement disorders

There are many rare movement disorders, and new ones are described every year. Because they are not well recognized, they often go undiagnosed for long periods of time. However, early diagnosis is becoming increasingly important. Rapid advances in our understanding of the biological mechanisms responsible for many rare disorders have enabled the development of specific treatments for some of them. Well-known historical examples include Wilson disease and dopa-responsive dystonia, for which specific and highly effective treatments have life-altering effects. In recent years, similarly specific and effective treatments have been developed for more than 30 rare inherited movement disorders. These treatments include specific medications, dietary changes, avoidance or management of certain triggers, enzyme replacement therapy, and others. This list of treatable rare movement disorders is likely to grow during the next few years because a number of additional promising treatments are actively being developed or evaluated in clinical trials. © 2017 International Parkinson and Movement Disorder Society.

GBA mutations in Parkinson disease: earlier death but similar neuropathological features

BACKGROUND AND PURPOSE

Mutations in the glucocerebrosidase (GBA) gene are known to be a risk factor for Parkinson's disease (PD). Data on clinicopathological correlation are limited. The purpose of this study was to determine the clinicopathological findings that might distinguish PD cases with and without mutations in the GBA gene.

METHODS

Data from the Arizona Study of Aging and Neurodegenerative Disorders were used to identify autopsied PD cases that did or did not have a GBA gene mutation. Clinical and neuropathological data were compared.

RESULTS

Twelve PD cases had a GBA mutation and 102 did not. The GBA mutation cases died younger (76 vs. 81 years of age) but there was no difference in disease duration or clinical examination findings. No neuropathological differences were found in total or regional semi-quantitative scores for Lewy-type synucleinopathy, senile plaques, neurofibrillary tangles, white matter rarefaction or cerebral amyloid angiopathy scores.

CONCLUSIONS

In longitudinally assessed, autopsied PD cases, those with GBA mutations had a younger age at death but there was no evidence for clinical or neuropathological differences compared to cases without GBA mutations. Due to the small GBA group size, small differences cannot be excluded.

A Review of Gaucher Disease Pathophysiology, Clinical Presentation and Treatments

Gaucher disease (GD, ORPHA355) is a rare, autosomal recessive genetic disorder. It is caused by a deficiency of the lysosomal enzyme, glucocerebrosidase, which leads to an accumulation of its substrate, glucosylceramide, in macrophages. In the general population, its incidence is approximately 1/40,000 to 1/60,000 births, rising to 1/800 in Ashkenazi Jews. The main cause of the cytopenia, splenomegaly, hepatomegaly, and bone lesions associated with the disease is considered to be the infiltration of the bone marrow, spleen, and liver by Gaucher cells. Type-1 Gaucher disease, which affects the majority of patients (90% in Europe and USA, but less in other regions), is characterized by effects on the viscera, whereas types 2 and 3 are also associated with neurological impairment, either severe in type 2 or variable in type 3. A diagnosis of GD can be confirmed by demonstrating the deficiency of acid glucocerebrosidase activity in leukocytes. Mutations in the GBA1 gene should be identified as they may be of prognostic value in some cases. Patients with type-1 GD-but also carriers of GBA1 mutation-have been found to be predisposed to developing Parkinson's disease, and the risk of neoplasia associated with the disease is still subject to discussion. Disease-specific treatment consists of intravenous enzyme replacement therapy (ERT) using one of the currently available molecules (imiglucerase, velaglucerase, or taliglucerase). Orally administered inhibitors of glucosylceramide biosynthesis can also be used (miglustat or eliglustat).

The biomarkers of immune dysregulation and inflammation response in Parkinson disease

Parkinson's disease (PD) is referring to the multi-systemic α-synucleinopathy with Lewy bodies deposited in midbrain. In ageing, the environmental and genetic factors work together and overactive major histocompatibility complex pathway to regulate immune reactions in central nerve system which resulting in neural degeneration, especially in dopaminergic neurons. As a series of biomarkers, the human leukocyte antigen genes with its related proteomics play cortical roles on the antigen presentation of major histocompatibility complex molecules to stimulate the differentiation of T lymphocytes and i-proteasome activities under their immune response to the PD-related environmental alteration and genetic variation. Furthermore, dopaminergic drugs change the biological characteristic of T lymphatic cells, affect the α-synuclein presentation pathway, and inhibit T lymphatic cells to release cytotoxicity in PD development. Taking together, the serum inflammatory factors and blood T cells are involved in the immune dysregulation of PD and inspected as the potential clinic biomarkers for PD prediction.