GBA Variants and Parkinson Disease: Mechanisms and Treatments

The Molecular Impact of Glucosylceramidase Beta 1 (Gba1) in Parkinson's Disease: a New Genetic State of the Art

Parkinson's disease (PD) is a neurodegenerative disorder affecting 2-3% of those aged over 65, characterized by motor symptoms like slow movement, tremors, and muscle rigidity, along with non-motor symptoms such as anxiety and dementia. Lewy bodies, clumps of misfolded proteins, contribute to neuron loss in PD. Mutations in the GBA1 gene are considered the primary genetic risk factor of PD. GBA1 mutations result in decreased activity of the lysosomal enzyme glucocerebrosidase (GCase) resulting in α-synuclein accumulation. We know that α-synuclein aggregation, lysosomal dysfunction, and endoplasmic reticulum disturbance are recognized factors to PD susceptibility; however, the molecular mechanisms connecting GBA1 gene mutations to increased PD risk remain partly unknown. Thus, in this narrative review conducted according to a systematic review method, we aimed to present the main contributions arising from the molecular impact of the GBA1 gene to the pathogenesis of PD providing new insights into potential impacts for advances in the clinical care of people with PD, a neurological disorder that has contributed to the substantial increase in the global burden of disease accentuated by the aging population. In summary, this narrative review highlights the multifaceted impact of GBA1 mutations in PD, exploring their role in clinical manifestations, genetic predispositions, and molecular mechanisms. The review emphasizes the importance of GBA1 mutations in both motor and non-motor symptoms of PD, suggesting broader therapeutic and management strategies. It also discusses the potential of CRISPR/Cas9 technology in advancing PD treatment and the need for future research to integrate these diverse aspects for improved diagnostics and therapies.

GBA-AAV mitigates sleep disruptions and motor deficits in mice with REM sleep behavior disorder

Sleep disturbances, including rapid eye movement sleep behavior disorder (RBD), excessive daytime sleepiness, and insomnia, are common non-motor manifestations of Parkinson's disease (PD). Little is known about the underlying mechanisms, partly due to the inability of current rodent models to adequately mimic the human PD sleep phenotype. Clinically, increasing studies have reported that variants of the glucocerebrosidase gene (GBA) increase the risk of PD. Here, we developed a mouse model characterized by sleep-wakefulness by injecting α-synuclein preformed fibronectin (PFF) into the sublaterodorsal tegmental nucleus (SLD) of GBA L444P mutant mice and investigated the role of the GBA L444P variant in the transition from rapid eye movement sleep behavior disorder to PD. Initially, we analyzed spectral correlates of REM and NREM sleep in GBA L444P mutant mice. Importantly, EEG power spectral analysis revealed that GBA L444P mutation mice exhibited reduced delta power during non-rapid eye movement (NREM) sleep and increased theta power (8.2-10 Hz) in active rapid eye movement (REM) sleep phases. Our study revealed that GBA L444P-mutant mice, after receiving PFF injections, exhibited increased sleep fragmentation, significant motor and cognitive dysfunctions, and loss of dopaminergic neurons in the substantia nigra. Furthermore, the over-expression of GBA-AAV partially improved these sleep disturbances and motor and cognitive impairments. In conclusion, we present the initial evidence that the GBA L444P mutant mouse serves as an essential tool in understanding the complex sleep disturbances associated with PD. This model further provides insights into potential therapeutic approaches, particularly concerning α-synuclein accumulation and its subsequent pathological consequences.

Interaction between caffeine consumption & genetic susceptibility in Parkinson's disease: A systematic review

BACKGROUND

Caffeine is one of the most consumed psychoactive substances globally. Caffeine-gene interactions in Parkinson's disease (PD) has not been systematically examined.

OBJECTIVES

To conduct a systematic review on the interaction between caffeine consumption and genetic susceptibility to PD.

METHODOLOGY

We conducted PubMed and Embase search using terms "Genetic association studies", "Caffeine", "polymorphism" and "Parkinson's disease", from inception till 2023. Of the initial 2391 studies, 21 case-control studies were included. The demographic, genetic and clinical data were extracted and analyzed.

RESULTS

We identified 21 studies which involved a total of 607,074 study subjects and 17 gene loci (SNCA, MAPT, HLA-DRA, NOS1, NOS3, GBA, ApoE, BST1, ESR2, NAT2, SLC2A13, LRRK2, NOS2A, GRIN2A, CYP1A2, ESR1, ADORA2A) have been investigated for the effect of gene-caffeine interaction and PD risk. The genes were identified through PD GWAS or involved in caffeine or related metabolism pathways. Based on the genetic association and interaction studies, only MAPT, SLC2A13, LRRK2, ApoE, NOS2A, GRIN2A, CYP1A2, and ADORA2A have been shown by at least one study to have a positive caffeine-gene interaction influencing the risk of PD.

CONCLUSION

Studies have shown an interaction between caffeine with genetic variants of MAPT, SLC2A13, LRRK2, ApoE, NOS2A, GRIN2A, CYP1A2, and ADORA2A in modulating the risk of PD. Due to the potential limitations of these discovery/pilot studies, further independent replication studies are needed. Better designed genetic association studies in multi-ancestry and admixed cohorts to identify potential shared or unique multivariate gene-environmental interactions, as well as functional studies of gene-caffeine interactions will be useful.

Iminosugar-Dihydroazulenes as Mutant L444P Glucocerebrosidase Enhancers

A remarkable enhancer of human glucocerebrosidase enzyme (GCase) was identified among a set of dihydroazulene-tagged iminosugars. An unprecedented 3.9-fold increase in GCase activity was detected on fibroblasts bearing the homozygous L444P mutation, which is frequently associated with neuronopathic Gaucher forms, and which commonly results refractory to chaperone-induced refolding.

Unveiling defects of secretion mechanisms in Parkinson's disease

Neurodegenerative diseases are characterized by progressive dysfunction and loss of specific sets of neurons. While extensive research has focused on elucidating the genetic and epigenetic factors and molecular mechanisms underlying these disorders, emerging evidence highlights the critical role of secretion in the pathogenesis, possibly even onset, and progression of neurodegenerative diseases, suggesting the occurrence of non-cell-autonomous mechanisms. Secretion is a fundamental process that regulates intercellular communication, supports cellular homeostasis, and orchestrates various physiological functions in the body. Defective secretion can impair the release of neurotransmitters and other signaling molecules, disrupting synaptic transmission and compromising neuronal survival. It can also contribute to the accumulation, misfolding, and aggregation of disease-associated proteins, leading to neurotoxicity and neuronal dysfunction. In this review, we discuss the implications of defective secretion in the context of Parkinson's disease, emphasizing its role in protein aggregation, synaptic dysfunction, extracellular vesicle secretion, and neuroinflammation. We propose a multiple-hit model whereby protein accumulation and secretory defects must be combined for the onset and progression of the disease.

Considering screening for hereditary cancer syndromes at the time of obstetrical prenatal carrier screening

Preconception and pregnancy represent a unique window of opportunity for women to engage with the health care system. This article explores the possibility of offering testing for cancer‐associated pathogenic variants on obstetrical carrier screening panels.

Quetiapine, Clozapine, and Pimavanserin Treatment Response in Monogenic Parkinson's Disease Psychosis: A Systematic Review

Psychotic symptoms frequently occur in idiopathic Parkinson's disease (PD) and often require treatment with antipsychotic therapy. Most antipsychotics have the potential to worsen the motor symptoms of PD; quetiapine, clozapine, and pimavanserin are commonly used for the treatment of idiopathic PD because these medications tend to be comparatively well tolerated. Although psychotic symptoms may also occur in monogenic forms of PD, no reviews have focused on the use of antipsychotic medications in this context. The objective of the present systematic review was to characterize the effectiveness and tolerability of quetiapine, clozapine, and pimavanserin in monogenic PD-associated psychosis. A literature search was performed with PubMed, Scopus, and Embase. The search yielded 24 eligible articles describing 30 individuals, although treatment response with respect to psychotic symptoms was described in only 11 cases; of these, six individuals experienced symptomatic improvement or remission (four with clozapine and two with quetiapine), two exhibited a poor therapeutic response (one to clozapine and one to quetiapine), and the other three responded initially to antipsychotic therapy before experiencing a recurrence of symptoms. The use of quetiapine and clozapine in GBA variant-associated PD is briefly reviewed separately. Notably, no reports of pimavanserin therapy were identified. In keeping with the idiopathic PD literature, relatively low doses of medication were used in most cases. Lastly, side effects were rarely reported. Although quetiapine and particularly clozapine may be effective and well tolerated in the treatment of monogenic PD psychosis, this review highlights the paucity of available evidence to guide clinical decision making in this context.

Upregulation of peroxisome proliferator-activated receptor γ with resorcinol alleviates reactive oxygen species generation and lipid accumulation in neuropathic lysosomal storage diseases

Neuropathic lysosomal storage diseases (NLSDs), including ceroid lipofuscinosis neuronal 3 (CLN3) disease and Gaucher disease type 2 (GD2), are typically present in adolescents; however, there are no approved therapies. CLN3 disease is the most common of the 13 types of neuronal ceroid lipofuscinosis, and Gaucher disease is the most common type of lysosomal storage disease. These NLSDs share oxidative stress and lysosomal dysfunction with Parkinson's disease. In this study, we used patient-derived cells (PDCs) and resorcinol to develop a therapeutic agent based on peroxisome proliferator-activated receptor γ (PPARγ) activation. PPARγ is a major regulator of autophagy and reactive oxygen species (ROS). Resorcinol, a polyphenolic compound, has been reported to exhibit PPARγ agonistic potential. Protein levels were analyzed by immunoblotting and immunofluorescence microscopy. Changes in cellular metabolism, including ROS levels, lipid droplet content, and lysosomal activity, were measured by flow cytometry. Resorcinol reduced ROS levels by suppressing hypoxia-inducible factor 1α levels in CLN3-PDCs. Resorcinol upregulated autophagy and reduced lipid accumulation in CLN3-PDCs; however, these effects were abolished by autophagy inhibitors. Resorcinol increased nuclear PPARγ levels in CLN3-PDCs, and PPARγ antagonists abolished the therapeutic effects of resorcinol. Moreover, Resorcinol upregulated nuclear PPARγ levels and lysosomal activity in GD2-PDCs, and reduced lipid accumulation and ROS levels. In summary, resorcinol alleviated the shared pathogenesis of CLN3 disease and GD2 through PPARγ upregulation. These findings suggest that resorcinol is a potential therapeutic candidate for alleviating NLSD progression.

Novel insights into the modulation of the voltage-gated potassium channel KV1.3 activation gating by membrane ceramides

Membrane lipids extensively modulate the activation gating of voltage-gated potassium channels (KV), however, much less is known about the mechanisms of ceramide and glucosylceramide actions including which structural element is the main intramolecular target and whether there is any contribution of indirect, membrane biophysics-related mechanisms to their actions. We used two-electrode voltage-clamp fluorometry capable of recording currents and fluorescence signals to simultaneously monitor movements of the pore domain (PD) and the voltage sensor domain (VSD) of the KV1.3 ion channel after attaching an MTS-TAMRA fluorophore to a cysteine introduced into the extracellular S3-S4 loop of the VSD. We observed rightward shifts in the conductance-voltage (G-V) relationship, slower current activation kinetics, and reduced current amplitudes in response to loading the membrane with C16-ceramide (Cer) or C16-glucosylceramide (GlcCer). When analyzing VSD movements, only Cer induced a rightward shift in the fluorescence signal-voltage (F-V) relationship and slowed fluorescence activation kinetics, whereas GlcCer exerted no such effects. These results point at a distinctive mechanism of action with Cer primarily targeting the VSD, while GlcCer only the PD of KV1.3. Using environment-sensitive probes and fluorescence-based approaches, we show that Cer and GlcCer similarly increase molecular order in the inner, hydrophobic regions of bilayers, however, Cer induces a robust molecular reorganization at the membrane-water interface. We propose that this unique ordering effect in the outermost membrane layer in which the main VSD rearrangement involving an outward sliding of the top of S4 occurs can explain the VSD targeting mechanism of Cer, which is unavailable for GlcCer.

Emerging perspectives on precision therapy for Parkinson's disease: multidimensional evidence leading to a new breakthrough in personalized medicine

PD is a prevalent and progressive neurodegenerative disorder characterized by both motor and non-motor symptoms. Genes play a significant role in the onset and progression of the disease. While the complexity and pleiotropy of gene expression networks have posed challenges for gene-targeted therapies, numerous pathways of gene variant expression show promise as therapeutic targets in preclinical studies, with some already in clinical trials. With the recognition of the numerous genes and complex pathways that can influence PD, it may be possible to take a novel approach to choose a treatment for the condition. This approach would be based on the symptoms, genomics, and underlying mechanisms of the disease. We discuss the utilization of emerging genetic and pathological knowledge of PD patients to categorize the disease into subgroups. Our long-term objective is to generate new insights for the therapeutic approach to the disease, aiming to delay and treat it more effectively, and ultimately reduce the burden on individuals and society.

Neurological symptoms in adults with Gaucher disease: a systematic review

INTRODUCTION

Gaucher disease (GD) is classically divided into three types, based on the presence or absence of neurological signs and symptoms. However, presentation can be highly variable in adulthood, and this aspect has not been adequately addressed in the literature so far. We performed a systematic literature review to analyze the entire spectrum of neurological manifestations in adult patients previously classified as GD type I, II, or III, evaluating the role of variants in different neurological manifestations.

METHODS

We searched databases for studies reporting clinical data of adult GD patients (age ≥ 18). Data extraction included GD types, GBA1 variants, age at disease onset and diagnosis, duration of GD, and age at onset and type of neurological symptoms reported.

RESULTS

Among 4190 GD patients from 85 studies, 555 exhibited neurological symptoms in adulthood. The median age at evaluation was 46.8 years (IQR 26.5), age at neurological symptoms onset was 44 years (IQR 35.1), and age at GD clinical onset was 23 years (IQR 23.4). Parkinsonism, including Parkinson's disease and Lewy Body dementia, was the most reported neurological manifestation. Other symptoms and signs encompassed oculomotor abnormalities, peripheral neuropathy, seizures, myoclonus, and cerebellar, cognitive and psychiatric symptoms. The genotype N370S/N370S mostly presented with Parkinsonism and the L444P variant with severe and earlier neurological symptoms.

CONCLUSION

The findings of this systematic review highlight: (1) the relevance of a comprehensive neurological assessment in GD patients, and (2) the importance of considering possible undiagnosed GD in adult patients with mild systemic symptoms presenting unexplained neurological symptoms.

GBA moderates cognitive reserve's effect on cognitive function in patients with Parkinson's disease

BACKGROUND

Cognitive reserve (CR) involves an individual's ability to maintain cognitive vitality over their lifespan. Glucocerebrosidase (GBA) gene mutations contribute to additional effects on cognitive function in Parkinson's disease (PD) patients, but the interplay between GBA mutations and CR remains unclear. We investigated the interactions among CR, GBA, and diseases, aiming to examine whether the CR established at different stages interacts with specific genotypes to affect cognitive function.

METHODS

Three hundred and eighteen participants' CR indicators (i.e., education, occupation, and social function) and comprehensive neuropsychological function (i.e., tests for executive function, attention/working memory, visuospatial function, memory, and language) were evaluated.

RESULTS

We found that CR established in a specific life stage influences the individual's cognitive function, particularly in PD, based on their distinct GBA rs9628662 genotypes. Attention/working memory and memory performance are affected by occupational complexity in midlife in PD patients with the GG genotype (q < 0.0001; q < 0.0001) and healthy adults with the T genotype (q = 0.0440; q < 0.0001). Language is influenced by early education and occupation, and the effects of occupation are also observed in PD patients with the GG genotype (q = 0.0040) and in healthy adults carrying the T genotype (q = 0.0040).

CONCLUSIONS

CR, established at different life stages, can be influenced by the GBA rs9628662 genotype, impacting later-life cognition. Validating genotypes and incorporating genotype information when assessing cognitive reserve effects is crucial and can enhance targeted cognitive training.

A benign course of Parkinson's disease associated with different mutations in the glucocerebrosidase gene - A case series

BACKGROUND

Subjects carrying mutations in the GBA gene, whether in one or two alleles pose a risk to develop Parkinson's disease (PD). This type of GBA-related PD has usually a severe course, and patients tend to develop cognitive deficits faster. Herein we describe 8 cases of GBA-PD patients with a markedly benign course (bGBA-PD), and compared them to the other regular GBA-PD group (rGBA-PD) and to mutation negative patients (MNP).

METHODS

All patients who performed next generation testing were enrolled. We defined bGBA-PD as patients with disease duration of at least 5 years, with Hoehn and Yahr (HY) ≤3 and MoCA score of ≥24. Following a selection of patients with a disease duration of 3 years or longer up to 15 years or shorter, we compared the bGBA-PD group to the rGBA-PD and MNP in terms of demographic and clinical features.

RESULTS

166 patients (58 males) diagnosed with PD were genotyped. Twenty-five patients were GBA-PD, of whom 7 were defined as bGBA-PD. Seventeen patients were LRRK2-PD and 123 patients were MNP. The rate of Rapide Eye Movement Behavioral Disorder (RBD) was highest in the rGBA-PD group and lowest in the bGBA-PD group (100 % vs. 28.6 %) (p < 0.001). The bGBA-PD group scored significantly higher in the Montreal Cognitive Assessment (MoCA) than rGBA-PD and MNP (27.6 ± 2.0 vs. 19.8 ± 3.9 vs. 23.5 ± 3.7, respectively; p = 0.006). There were no significant differences in MDS-UPDRS part-3 among the groups. There was no specific GBA mutation which was more commonly associated with bGBA-PD.

CONCLUSION

While GBA-PD has a severe course of disease, a subgroup of which shows a benign course with a relatively preserved cognitive function even years after onset. We might suggest that these cases have other pathomechanisms leading to PD, including an incidental GBA carriership.

GBA1-Associated Parkinson's Disease Is a Distinct Entity

GBA1-associated Parkinson's disease (GBA1-PD) is increasingly recognized as a distinct entity within the spectrum of parkinsonian disorders. This review explores the unique pathophysiological features, clinical progression, and genetic underpinnings that differentiate GBA1-PD from idiopathic Parkinson's disease (iPD). GBA1-PD typically presents with earlier onset and more rapid progression, with a poor response to standard PD medications. It is marked by pronounced cognitive impairment and a higher burden of non-motor symptoms compared to iPD. Additionally, patients with GBA1-PD often exhibit a broader distribution of Lewy bodies within the brain, accentuating neurodegenerative processes. The pathogenesis of GBA1-PD is closely associated with mutations in the GBA1 gene, which encodes the lysosomal enzyme beta-glucocerebrosidase (GCase). In this review, we discuss two mechanisms by which GBA1 mutations contribute to disease development: 'haploinsufficiency,' where a single functional gene copy fails to produce a sufficient amount of GCase, and 'gain of function,' where the mutated GCase acquires harmful properties that directly impact cellular mechanisms for alpha-synuclein degradation, leading to alpha-synuclein aggregation and neuronal cell damage. Continued research is advancing our understanding of how these mechanisms contribute to the development and progression of GBA1-PD, with the 'gain of function' mechanism appearing to be the most plausible. This review also explores the implications of GBA1 mutations for therapeutic strategies, highlighting the need for early diagnosis and targeted interventions. Currently, small molecular chaperones have shown the most promising clinical results compared to other agents. This synthesis of clinical, pathological, and molecular aspects underscores the assertion that GBA1-PD is a distinct clinical and pathobiological PD phenotype, necessitating specific management and research approaches to better understand and treat this debilitating condition.

An AAV capsid reprogrammed to bind human transferrin receptor mediates brain-wide gene delivery

Developing vehicles that efficiently deliver genes throughout the human central nervous system (CNS) will broaden the range of treatable genetic diseases. We engineered an adeno-associated virus (AAV) capsid, BI-hTFR1, that binds human transferrin receptor (TfR1), a protein expressed on the blood-brain barrier. BI-hTFR1 was actively transported across human brain endothelial cells and, relative to AAV9, provided 40 to 50 times greater reporter expression in the CNS of human TFRC knockin mice. The enhanced tropism was CNS-specific and absent in wild-type mice. When used to deliver GBA1, mutations of which cause Gaucher disease and are linked to Parkinson's disease, BI-hTFR1 substantially increased brain and cerebrospinal fluid glucocerebrosidase activity compared with AAV9. These findings establish BI-hTFR1 as a potential vector for human CNS gene therapy.

An Overview of Epigenetic Changes in the Parkinson's Disease Brain

Parkinson's disease is a progressive neurodegenerative disorder, predominantly of the motor system. Although some genetic components and cellular mechanisms of Parkinson's have been identified, much is still unknown. In recent years, emerging evidence has indicated that non-DNA-sequence variation (in particular epigenetic mechanisms) is likely to play a crucial role in the development and progression of the disease. Here, we present an up-to-date overview of epigenetic processes including DNA methylation, DNA hydroxymethylation, histone modifications and non-coding RNAs implicated in the brain of those with Parkinson's disease. We will also discuss the limitations of current epigenetic research in Parkinson's disease, the advantages of simultaneously studying genetics and epigenetics, and putative novel epigenetic therapies.

GBA-associated Parkinson's disease in Hungary: clinical features and genetic insights

INTRODUCTION

Parkinson's disease (PD) has a complex genetic background involving both rare and common genetic variants. Although a small percentage of cases show a clear Mendelian inheritance pattern, it is much more relevant to identify patients who present with a complex genetic profile of risk variants with different severity. The ß-glucocerebrosidase coding gene (GBA1) is recognized as the most frequent genetic risk factor for PD and Lewy body dementia, irrespective of reduction of the enzyme activity due to genetic variants.

METHODS

In a selected cohort of 190 Hungarian patients with clinical signs of PD and suspected genetic risk, we performed the genetic testing of the GBA1 gene. As other genetic hits can modify clinical features, we also screened for additional rare variants in other neurodegenerative genes and assessed the APOE-ε genotype of the patients.

RESULTS

In our cohort, we identified 29 GBA1 rare variant (RV) carriers. Out of the six different detected RVs, the highly debated E365K and T408M variants are composed of the majority of them (22 out of 32). Three patients carried two GBA1 variants, and an additional three patients carried rare variants in other neurodegenerative genes (SMPD1, SPG11, and SNCA). We did not observe differences in age at onset or other clinical features of the patients carrying two GBA1 variants or patients carrying heterozygous APOE-ε4 allele.

CONCLUSION

We need further studies to better understand the drivers of clinical differences in these patients, as this could have important therapeutic implications.

Plasma exosomes impair microglial degradation of α-synuclein through V-ATPase subunit V1G1

INTRODUCTION

Microglia are the main phagocytes in the brain and can induce neuroinflammation. Moreover, they are critical to alpha-synuclein (α-syn) aggregation and propagation. Plasma exosomes derived from patients diagnosed with Parkinson's disease (PD-exo) reportedly evoked α-syn aggregation and inflammation in microglia. In turn, microglia internalized and released exosomal α-syn, enhancing α-syn propagation. However, the specific mechanism through which PD-exo influences α-syn degradation remains unknown.

METHODS

Exosomes were extracted from the plasma of patients with PD by differential ultracentrifugation, analyzed using electron microscopy (EM) and nanoparticle flow cytometry, and stereotaxically injected into the unilateral striatum of the mice. Transmission EM was employed to visualize lysosomes and autophagosomes in BV2 cells, and lysosome pH was measured with LysoSensor Yellow/Blue DND-160. Cathepsin B and D, lysosomal-associated membrane protein 1 (LAMP1), ATP6V1G1, tumor susceptibility gene 101 protein, calnexin, α-syn, ionized calcium binding adaptor molecule 1, and NLR family pyrin domain containing 3 were evaluated using quantitative polymerase chain reaction or western blotting, and α-syn, LAMP1, and ATP6V1G1 were also observed by immunofluorescence. Small interfering ribonucleic acid against V1G1 was transfected into BV2 cells and primary microglia using Lipofectamine® 3000. A PD mouse model was established via injection with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) into mice. A lentiviral-mediated strategy to overexpress ATP6V1G1 in the brain of MPTP-treated mice was employed. Motor coordination was assessed using rotarod and pole tests, and neurodegeneration in the mouse substantia nigra and striatum tissues was determined using immunofluorescence histochemical and western blotting of tyrosine hydroxylase.

RESULTS

PD-exo decreased the expression of V1G1, responsible for the acidification of intra- and extracellular milieu. This impairment of lysosomal acidification resulted in the accumulation of abnormally swollen lysosomes and decreased lysosomal enzyme activities, impairing lysosomal protein degradation and causing α-syn accumulation. Additionally, V1G1 overexpression conferred the mice neuroprotection during MPTP exposure.

CONCLUSION

Pathogenic protein accumulation is a key feature of PD, and compromised V-type ATPase dysfunction might participate in PD pathogenesis. Moreover, V1G1 overexpression protects against neuronal toxicity in an MPTP-based PD mouse model, which may provide opportunities to develop novel therapeutic interventions for PD treatment.

Towards a Global View of Parkinson's Disease Genetics

Parkinson's disease (PD) is a global health challenge, yet historically studies of PD have taken place predominantly in European populations. Recent genetics research conducted in non-European populations has revealed novel population-specific genetic loci linked to PD risk, highlighting the importance of studying PD globally. These insights have broadened our understanding of PD etiology, which is crucial for developing disease-modifying interventions. This review comprehensively explores the global genetic landscape of PD, emphasizing the scientific rationale for studying underrepresented populations. It underscores challenges, such as genotype-phenotype heterogeneity and inclusion difficulties for non-European participants, emphasizing the ongoing need for diverse and inclusive research in PD. ANN NEUROL 2024;95:831-842.

Unraveling Dysregulated Cell Signaling Pathways, Genetic and Epigenetic Mysteries of Parkinson's Disease

Parkinson's disease (PD) is a prevalent and burdensome neurodegenerative disorder that has been extensively researched to understand its complex etiology, diagnosis, and treatment. The interplay between genetic and environmental factors in PD makes its pathophysiology difficult to comprehend, emphasizing the need for further investigation into genetic and epigenetic markers involved in the disease. Early diagnosis is crucial for optimal management of the disease, and the development of novel diagnostic biomarkers is ongoing. Although many efforts have been made in the field of recognition and interpretation of the mechanisms involved in the pathophysiology of the disease, the current knowledge about PD is just the tip of the iceberg. By scrutinizing genetic and epigenetic patterns underlying PD, new avenues can be opened for dissecting the pathology of the disorder, leading to more precise and efficient diagnostic and therapeutic approaches. This review emphasizes the importance of studying dysregulated cell signaling pathways and molecular processes associated with genes and epigenetic alterations in understanding PD, paving the way for the development of novel therapeutic strategies to combat this devastating disease.

Prodromal multiple sclerosis: considerations and future utility

A multiple sclerosis (MS) prodrome has recently been described and is characterised by increased rates of healthcare utilisation and an excess frequency of fatigue, bladder problems, sensory symptoms and pain, in the years leading up to clinical onset of disease. This important observation may have several potential applications including in the identification of risk factors for disease, the potential to delay or prevent disease onset and early opportunities to alter disease course. It may also offer possibilities for the use of risk stratification algorithms and effective population screening. If standardised, clearly defined and disease specific, an MS prodrome is also likely to have a profound influence on research and clinical trials directed at the earliest stages of disease. In order to achieve these goals, it is essential to consider experience already gleaned from other disorders. More specifically, in some chronic neurological disorders the understanding of disease pro-drome is now well advanced and has been successfully applied. However, understanding of the MS prodrome remains at an early stage with key questions including the length of the prodrome, symptom specificity and potential benefits of early intervention as yet unanswered. In this review we will explore the evidence available to date and suggest future research strategies to address unanswered questions. In addition, whilst current understanding of the MS prodrome is not yet sufficient to justify changes in public health policy or MS management, we will consider the practical utility and future application of the MS prodrome in a wider health care setting.

Biomarkers for Managing Neurodegenerative Diseases

Neurological disorders are the leading cause of cognitive and physical disability worldwide, affecting 15% of the global population. Due to the demographics of aging, the prevalence of neurological disorders, including neurodegenerative diseases, will double over the next two decades. Unfortunately, while available therapies provide symptomatic relief for cognitive and motor impairment, there is an urgent unmet need to develop disease-modifying therapies that slow the rate of pathological progression. In that context, biomarkers could identify at-risk and prodromal patients, monitor disease progression, track responses to therapy, and parse the causality of molecular events to identify novel targets for further clinical investigation. Thus, identifying biomarkers that discriminate between diseases and reflect specific stages of pathology would catalyze the discovery and development of therapeutic targets. This review will describe the prevalence, known mechanisms, ongoing or recently concluded therapeutic clinical trials, and biomarkers of three of the most prevalent neurodegenerative diseases, including Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), and Parkinson's disease (PD).

Genetics in Parkinson's disease, state-of-the-art and future perspectives

BACKGROUND

Parkinson's disease (PD) is the second most common neurodegenerative disorder and is clinically characterized by the presence of motor (bradykinesia, rigidity, rest tremor and postural instability) and non-motor symptoms (cognitive impairment, autonomic dysfunction, sleep disorders, depression and hyposmia). The aetiology of PD is unknown except for a small but significant contribution of monogenic forms.

SOURCES OF DATA

No new data were generated or analyzed in support of this review.

AREAS OF AGREEMENT

Up to 15% of PD patients carry pathogenic variants in PD-associated genes. Some of these genes are associated with mendelian inheritance, while others act as risk factors. Genetic background influences age of onset, disease course, prognosis and therapeutic response.

AREAS OF CONTROVERSY

Genetic testing is not routinely offered in the clinical setting, but it may have relevant implications, especially in terms of prognosis, response to therapies and inclusion in clinical trials. Widely adopted clinical guidelines on genetic testing are still lacking and open to debate. Some new genetic associations are still awaiting confirmation, and selecting the appropriate genes to be included in diagnostic panels represents a difficult task. Finally, it is still under study whether (and to which degree) specific genetic forms may influence the outcome of PD therapies.

GROWING POINTS

Polygenic Risk Scores (PRS) may represent a useful tool to genetically stratify the population in terms of disease risk, prognosis and therapeutic outcomes.

AREAS TIMELY FOR DEVELOPING RESEARCH

The application of PRS and integrated multi-omics in PD promises to improve the personalized care of patients.

Peripheral Upregulation of Parkinson's Disease-Associated Genes Encoding α-Synuclein, β-Glucocerebrosidase, and Ceramide Glucosyltransferase in Major Depression

Due to the high comorbidity of Parkinson's disease (PD) with major depressive disorder (MDD) and the involvement of sphingolipids in both conditions, we investigated the peripheral expression levels of three primarily PD-associated genes: α-synuclein (SNCA), lysosomal enzyme β-glucocerebrosidase (GBA1), and UDP-glucose ceramide glucosyltransferase (UGCG) in a sex-balanced MDD cohort. Normalized gene expression was determined by quantitative PCR in patients suffering from MDD (unmedicated n = 63, medicated n = 66) and controls (remitted MDD n = 39, healthy subjects n = 61). We observed that expression levels of SNCA (p = 0.036), GBA1 (p = 0.014), and UGCG (p = 0.0002) were higher in currently depressed patients compared to controls and remitted patients, and expression of GBA1 and UGCG decreased in medicated patients during three weeks of therapy. Additionally, in subgroups, expression was positively correlated with the severity of depression and anxiety. Furthermore, we identified correlations between the gene expression levels and PD-related laboratory parameters. Our findings suggest that SNCA, GBA1, and UGCG analysis could be instrumental in the search for biomarkers of MDD and in understanding the overlapping pathological mechanisms underlying neuro-psychiatric diseases.

A Brazilian Rare-Disease Center's Experience with Glucosylsphingosine (lyso-Gb1) in Patients with Gaucher Disease: Exploring a Novel Correlation with IgG Levels in Plasma and a Biomarker Measurement in CSF

Gaucher disease (GD, OMIM 230800) is one of the most common lysosomal disorders, being caused by the deficient activity of the enzyme acid β-glucocerebrosidase (Gcase). Three clinical forms of Gaucher's disease (GD) are classified based on neurological involvement. Type 1 (GD1) is non-neuronopathic, while types 2 (GD2) and 3 (GD3) are neuronopathic forms. Gcase catalyzes the conversion of glucosylceramide (GlcCer) into ceramide and glucose. As GlcCer accumulates in lysosomal macrophages, it undergoes deacylation to become glycosylsphingosine (lyso-Gb1), which has shown to be a useful and reliable biomarker for the diagnosis and monitoring of treated and untreated patients with GD. Multiple myeloma (MM) is one of the leading causes of cancer-related death among patients with GD and monoclonal gammopathy of undetermined significance (MGUS) is a non-neoplastic condition that can be a telltale sign of a B clonal proliferation caused by the chronic activation of B cells. This study aimed to quantify Lyso-Gb1 levels in dried blood spots (DBS) and cerebrospinal fluid (CSF) as biomarkers for Gaucher disease (GD) and discuss the association of this biomarker with other clinical parameters. This is a mixed-methods study incorporating both cross-sectional and longitudinal elements within a cohort design with a convenience-sampling strategy. Data collection took place from January 2012 to March 2023. Lyso-Gb1 extraction from DBS involved the use of a methanol-acetonitrile-water mixture, followed by incubation and centrifugation. Analysis was performed using UPLC-MS/MS with MassLynx software version 4.2 and the control group for the DBS measurements included general newborns. CSF Lyso-Gb1 was extracted using ethyl acetate, analyzed by UPLC-MS/MS with a calibration curve, and expressed in pmol/L. Lysosomal activity in CSF was assessed by measuring chitotriosidase (Cht), and other lysosomal enzyme activities were assessed as previously described in the literature. Patients with metachromatic leukodystrophy (MLD) were used as controls. Thirty-two treated patients (twenty-nine GD1 and three GD3, all on ERT except for one GD type on SRT with eliglustat) and three untreated patients (one GD1, one GD2, and one GD3) were included. When analyzing only the treated GD1 group, a significant correlation was found between lyso-Gb1 and age (rho = -0.447, p = 0.001), ChT, and IgG levels (rho = 0.73, p < 0.001; and rho = 0.36, p = 0.03, respectively). Five GD1 patients (three females, mean age 40 years) also had their CSF collected and analyzed. The average measurement of lyso-Gb1 in CSF was 94 pmol/L (range: 57.1-157.9 pmol/L) versus <6.2 pmol/L in the control group (MLD). This is the first time, to the best of our knowledge, that lyso-Gb1 has been associated with IgG levels. While this finding reflects a risk for MGUS or MM and not only chronic plasma B-cell activation, it still requires further studies. Moreover, the analysis of CSF lyso-Gb1 levels in GD1 patients was demonstrated to be significantly higher than the control group. This raises the hypothesis that CSF lyso-Gb1 may serve as a valuable indicator for neurological involvement in GD, providing insights into the potential implications for neurological manifestations in GD, including GD1. The correlation between lyso-Gb1 and ChT levels in treated GD1 patients further underscores the interconnectedness of lysosomal markers and their relevance in monitoring.

Neuroinflammation is linked to dementia risk in Parkinson's disease

The development of dementia is a devastating aspect of Parkinson's disease (PD), affecting nearly half of patients within 10 years post-diagnosis. For effective therapies to prevent and slow progression to PD dementia (PDD), the key mechanisms that determine why some people with PD develop early dementia, while others remain cognitively unaffected, need to be understood. Neuroinflammation and tau protein accumulation have been demonstrated in post-mortem PD brains, and in many other neurodegenerative disorders leading to dementia. However, whether these processes mediate dementia risk early on in the PD disease course is not established. To this end, we used PET neuroimaging with 11C-PK11195 to index neuroinflammation and 18F-AV-1451 for misfolded tau in early PD patients, stratified according to dementia risk in our 'Neuroinflammation and Tau Accumulation in Parkinson's Disease Dementia' (NET-PDD) study. The NET-PDD study longitudinally assesses newly-diagnosed PD patients in two subgroups at low and high dementia risk (stratified based on pentagon copying, semantic fluency, MAPT genotype), with comparison to age- and sex-matched controls. Non-displaceable binding potential (BPND) in 43 brain regions (Hammers' parcellation) was compared between groups (pairwise t-tests), and associations between BPND of the tracers tested (linear-mixed-effect models). We hypothesized that people with higher dementia risk have greater inflammation and/or tau accumulation in advance of significant cognitive decline. We found significantly elevated neuroinflammation (11C-PK11195 BPND) in multiple subcortical and restricted cortical regions in the high dementia risk group compared with controls, while in the low-risk group this was limited to two cortical areas. The high dementia risk group also showed significantly greater neuroinflammation than the low-risk group concentrated on subcortical and basal ganglia regions. Neuroinflammation in most of these regions was associated with worse cognitive performance (Addenbrooke's Cognitive Examination-III score). Overall neuroinflammation burden also correlated with serum levels of pro-inflammatory cytokines. In contrast, increases in 18F-AV-1451 (tau) BPND in PD versus controls were restricted to subcortical regions where off-target binding is typically seen, with no relationship to cognition found. Whole-brain 18F-AV-1451 burden correlated with serum phosphorylated tau181 levels. Although there was minimal regional tau accumulation in PD, regional neuroinflammation and tau burden correlated in PD participants, with the strongest association in the high dementia risk group, suggesting possible co-localization of these pathologies. In conclusion, our findings suggest that significant regional neuroinflammation in early PD might underpin higher risk for PDD development, indicating neuroinflammation as a putative early modifiable aetiopathological disease factor to prevent or slow dementia development using immunomodulatory strategies.

Inhibition of striatal dopamine release by the L-type calcium channel inhibitor isradipine co-varies with risk factors for Parkinson's

Ca2+ entry into nigrostriatal dopamine (DA) neurons and axons via L-type voltage-gated Ca2+ channels (LTCCs) contributes, respectively, to pacemaker activity and DA release and has long been thought to contribute to vulnerability to degeneration in Parkinson's disease. LTCC function is greater in DA axons and neurons from substantia nigra pars compacta than from ventral tegmental area, but this is not explained by channel expression level. We tested the hypothesis that LTCC control of DA release is governed rather by local mechanisms, focussing on candidate biological factors known to operate differently between types of DA neurons and/or be associated with their differing vulnerability to parkinsonism, including biological sex, α-synuclein, DA transporters (DATs) and calbindin-D28k (Calb1). We detected evoked DA release ex vivo in mouse striatal slices using fast-scan cyclic voltammetry and assessed LTCC support of DA release by detecting the inhibition of DA release by the LTCC inhibitors isradipine or CP8. Using genetic knockouts or pharmacological manipulations, we identified that striatal LTCC support of DA release depended on multiple intersecting factors, in a regionally and sexually divergent manner. LTCC function was promoted by factors associated with Parkinsonian risk, including male sex, α-synuclein, DAT and a dorsolateral co-ordinate, but limited by factors associated with protection, that is, female sex, glucocerebrosidase activity, Calb1 and ventromedial co-ordinate. Together, these data show that LTCC function in DA axons and isradipine effect are locally governed and suggest they vary in a manner that in turn might impact on, or reflect, the cellular stress that leads to parkinsonian degeneration.

New insight on the possible role of statins in Vascular Parkinsonism: A need for presumptive therapy

Vascular Parkinsonism (VP) is clinical term represents a progressive ischemic changes and subcortical lacunar infarct leading to Parkinsonism mainly in the lower limbs so called lower body Parkinsonism. The VP neuropathology is differed from that of PD neuropathology which rarely associated with basal ganglion lesions. Dopamine transporters are normal in VP but are highly reduced in PD, and dopaminergic agonists had no effective role on VP. The neuropathological mechanisms of VP are related to vascular injury which induces the interruption of the neural connection between basal ganglion and cerebral cortex. Hyperlipidemia and other cardiometabolic risk factors augment VP risk and the related neuropathology. Targeting of these cardiometabolic disorders by lipid-lowering statins may be effective in the management of VP. Therefore, this mini-review aims to clarify the possible role of statins in the management of VP. Statins have neuroprotective effects against different neurodegenerative diseases by anti-inflammatory, antioxidant and antithrombotic effects with enhancement of endothelial function. In conclusion, statins can prevent and treat VP by inhibiting inflammatory and oxidative stress disorders, mitigating of white matter hyperintensities and improving of neuronal signaling pathways. Additional preclinical, clinical trials and prospective studies are warranted in this regard.

Synaptic dysfunction and extracellular matrix dysregulation in dopaminergic neurons from sporadic and E326K-GBA1 Parkinson's disease patients

Parkinson's disease (PD) is a neurodegenerative disease with both genetic and sporadic origins. In this study, we investigated the electrophysiological properties, synaptic activity, and gene expression differences in dopaminergic (DA) neurons derived from induced pluripotent stem cells (iPSCs) of healthy controls, sporadic PD (sPD) patients, and PD patients with E326K-GBA1 mutations. Our results demonstrate reduced sodium currents and synaptic activity in DA neurons derived from PD patients with E326K-GBA1 mutations, suggesting a potential contribution to PD pathophysiology. We also observed distinct electrophysiological alterations in sPD DA neurons, which included a decrease in synaptic currents. RNA sequencing analysis revealed unique dysregulated pathways in sPD neurons and E326K-GBA1 neurons, further supporting the notion that molecular mechanisms driving PD may differ between PD patients. In agreement with our previous reports, Extracellular matrix and Focal adhesion pathways were among the top dysregulated pathways in DA neurons from sPD patients and from patients with E326K-GBA1 mutations. Overall, our study further confirms that impaired synaptic activity is a convergent functional phenotype in DA neurons derived from PD patients across multiple genetic mutations as well as sPD. At the transcriptome level, we find that the brain extracellular matrix is highly involved in PD pathology across multiple PD-associated mutations as well as sPD.

The pathogenesis of Parkinson's disease

Parkinson's disease is a progressive neurodegenerative condition associated with the deposition of aggregated α-synuclein. Insights into the pathogenesis of Parkinson's disease have been derived from genetics and molecular pathology. Biochemical studies, investigation of transplanted neurons in patients with Parkinson's disease, and cell and animal model studies suggest that abnormal aggregation of α-synuclein and spreading of pathology between the gut, brainstem, and higher brain regions probably underlie the development and progression of Parkinson's disease. At a cellular level, abnormal mitochondrial, lysosomal, and endosomal function can be identified in both monogenic and sporadic Parkinson's disease, suggesting multiple potential treatment approaches. Recent work has also highlighted maladaptive immune and inflammatory responses, possibly triggered in the gut, that accelerate the pathogenesis of Parkinson's disease. Although there are currently no disease-modifying treatments for Parkinson's disease, we now have a solid basis for the development of rational neuroprotective therapies that we hope will halt the progression of this disabling neurological condition.

Neurologic involvement in cystinosis: Focus on brain lesions and new evidence of four-repeat (4R-) Tau immunoreactivity

Nephropathic cystinosis is a rare autosomal recessive storage disorder caused by CTNS gene mutations, leading to autophagy-lysosomal pathway impairment and cystine crystals accumulation. Neurologic involvement is highly variable and includes both neurodevelopmental and neurodegenerative disturbances, as well as focal neurologic deficits. By presenting longitudinal data of a 28-year-old patient with a large infratentorial lesion, we summarized the pathology, clinical and imaging features of neurological involvement in cystinosis patients. Brain damage in form of cystinosis-related cerebral lesions occurs in advanced disease phases and is characterized by the accumulation of cystine crystals, subsequent inflammation with vasculitis-like features, necrosis, and calcification. Epilepsy is a frequent comorbidity in affected individuals. Steroids might play a role in the symptomatic treatment of "stroke-like" episodes due to edematous-inflammatory lesions, but probably do not change the overall prognosis. Lifelong compliance to depleting therapy with cysteamine still represents the main therapeutic option. However, consequences of CTNS gene defects are not restricted to cystine accumulation. New evidence of four-repeat (4R-) Tau immunoreactivity suggests concurrent progressive neurodegeneration in cystinosis patients, highlighting the need of innovative therapeutic strategies, and shedding light on the crosstalk between proteinopathies and autophagy-lysosomal system defects. Eventually, emerging easily accessible biomarkers such as serum neurofilament light chains (NfL) might detect subclinical neurologic involvement in cystinosis patients.

Occupational Pesticide Exposure in Parkinson's Disease Related to GBA and LRRK2 Variants

Background

The penetrance of common genetic risk variants for Parkinson's disease (PD) is low. Pesticide exposure increases PD risk, but how exposure affects penetrance is not well understood.

Objective

To determine the relationship between occupational pesticide exposure and PD in people with LRRK2 and GBA risk variants.

Methods

Participants of the Parkinson's Progression Markers Initiative (PPMI) with a LRRK2-G2019 S or GBA risk variant provided information about occupational pesticide exposure. We compared exposure in carriers with and without PD. Among carriers with PD, we used Cox proportional hazard models to compare time-to impairment in balance, cognition, and activities of daily living (ADLs) between participants with and without prior occupational pesticide exposure.

Results

378 participants with a risk variant provided exposure information; 176 with LRRK2-G2019 S (54 with and 122 without PD) and 202 with GBA variants (47 with and 155 without PD). Twenty-six participants reported pesticide exposure. People with a GBA variant and occupational pesticide exposure had much higher odds of PD (aOR: 5.4, 95% CI 1.7-18.5, p < 0.01). People with a LRRK2 variant and a history of occupational pesticide exposure had non-significantly elevated odds of PD (aOR 1.3, 95% CI 0.4-4.6, p = 0.7). Among those with PD, pesticide exposure was associated with a higher risk of balance problems and cognitive impairment in LRRK2-PD and functional impairment in GBA-PD, although associations were not statistically significant.

Conclusions

Occupational pesticide exposure may increase penetrance of GBA-PD and may be associated with faster symptom progression. Further studies in larger cohorts are necessary.

Modeling familial and sporadic Parkinson's disease in small fishes

The establishment of animal models for Parkinson's disease (PD) has been challenging. Nevertheless, once established, they will serve as valuable tools for elucidating the causes and pathogenesis of PD, as well as for developing new strategies for its treatment. Following the recent discovery of a series of PD causative genes in familial cases, teleost fishes, including zebrafish and medaka, have often been used to establish genetic PD models because of their ease of breeding and gene manipulation, as well as the high conservation of gene orthologs. Some of the fish lines can recapitulate PD phenotypes, which are often more pronounced than those in rodent genetic models. In addition, a new experimental teleost fish, turquoise killifish, can be used as a sporadic PD model, because it spontaneously manifests age-dependent PD phenotypes. Several PD fish models have already made significant contributions to the discovery of novel PD pathological features, such as cytosolic leakage of mitochondrial DNA and pathogenic phosphorylation in α-synuclein. Therefore, utilizing various PD fish models with distinct degenerative phenotypes will be an effective strategy for identifying emerging facets of PD pathogenesis and therapeutic modalities.

An AAV capsid reprogrammed to bind human Transferrin Receptor mediates brain-wide gene delivery

Developing vehicles that efficiently deliver genes throughout the human central nervous system (CNS) will broaden the range of treatable genetic diseases. We engineered an AAV capsid, BI-hTFR1, that binds human Transferrin Receptor (TfR1), a protein expressed on the blood-brain barrier (BBB). BI-hTFR1 was actively transported across a human brain endothelial cell layer and, relative to AAV9, provided 40-50 times greater reporter expression in the CNS of human TFRC knock-in mice. The enhanced tropism was CNS-specific and absent in wild type mice. When used to deliver GBA1, mutations of which cause Gaucher disease and are linked to Parkinson's disease, BI-hTFR1 substantially increased brain and cerebrospinal fluid glucocerebrosidase activity compared to AAV9. These findings establish BI-hTFR1 as a promising vector for human CNS gene therapy.

Untargeted serum metabolomics reveals novel metabolite associations and disruptions in amino acid and lipid metabolism in Parkinson's disease

BACKGROUND

Untargeted high-resolution metabolomic profiling provides simultaneous measurement of thousands of metabolites. Metabolic networks based on these data can help uncover disease-related perturbations across interconnected pathways.

OBJECTIVE

Identify metabolic disturbances associated with Parkinson's disease (PD) in two population-based studies using untargeted metabolomics.

METHODS

We performed a metabolome-wide association study (MWAS) of PD using serum-based untargeted metabolomics data derived from liquid chromatography with high-resolution mass spectrometry (LC-HRMS) using two distinct population-based case-control populations. We also combined our results with a previous publication of 34 metabolites linked to PD in a large-scale, untargeted MWAS to assess external validation.

RESULTS

LC-HRMS detected 4,762 metabolites for analysis (HILIC: 2716 metabolites; C18: 2046 metabolites). We identified 296 features associated with PD at FDR<0.05, 134 having a log2 fold change (FC) beyond ±0.5 (228 beyond ±0.25). Of these, 104 were independently associated with PD in both discovery and replication studies at p<0.05 (170 at p<0.10), while 27 were associated with levodopa-equivalent dose among the PD patients. Intriguingly, among the externally validated features were the microbial-related metabolites, p-cresol glucuronide (FC=2.52, 95% CI=1.67, 3.81, FDR=7.8e-04) and p-cresol sulfate. P-cresol glucuronide was also associated with motor symptoms among patients. Additional externally validated metabolites associated with PD include phenylacetyl-L-glutamine, trigonelline, kynurenine, biliverdin, and pantothenic acid. Novel associations include the anti-inflammatory metabolite itaconate (FC=0.79, 95% CI=0.73, 0.86; FDR=2.17E-06) and cysteine-S-sulfate (FC=1.56, 95% CI=1.39, 1.75; FDR=3.43E-11). Seventeen pathways were enriched, including several related to amino acid and lipid metabolism.

CONCLUSIONS

Our results revealed PD-associated metabolites, confirming several previous observations, including for p-cresol glucuronide, and newly implicating interesting metabolites, such as itaconate. Our data also suggests metabolic disturbances in amino acid and lipid metabolism and inflammatory processes in PD.

Sex distribution and classification of GBA1 variants in an Italian cohort of Parkinson's disease patients analyzed over the last seventeen years

INTRODUCTION

Heterozygous GBA1 variants are among the most frequent genetic risk factors for Parkinson's disease (PD). Male sex is a risk factor in the development of PD but the sex prevalence of GBA1 carriers in PD patients remains debatable. Molecular analysis of the GBA1 gene is complicated by the presence of a highly homologous pseudogene GBAP1.

METHOD

Starting from 2006, we screened GBA1 gene in a large cohort of 1762 PD patients through different techniques developed over the years. Identified variants were classified employing the GBA1-PD browser and compared on the basis of frequency and sex distribution.

RESULTS

Within a group of 684 patients (40.2% Males -M-) analyzed with RFLP technique looking for the two most common GBA1 mutations L444P and N370S, 29 resulted positive (4.23%). Out of 537 patients (67.4% M) analyzed with PCR that amplifies the portion of the gene between exon 8 and exon 11, we found 53 positive carriers (9.87%). Out of 424 patients (60.8% M) analyzed with NGS custom gene panel with allele-specific PCR, 50 resulted positive (11.79%). Since 2022, we also analyzed 117 patients (56.4% M) with long PCR sequenced with NGS, identifying 17 positive samples (14.52%).

CONCLUSION

In our study, we highlight that screening the entire GBA1 gene with specific techniques increases the diagnostic rate. Regarding variants distribution, males have shown a higher frequency of the severe variants and complex alleles, whereas mild variants are equally distributed in both sexes and risk variants are more frequent in females especially the T369 M.

The Role of Immune Dysfunction in Parkinson's Disease Development

Recent research has unveiled intriguing insights suggesting that the body's immune system may be implicated in Parkinson's disease (PD) development. Studies have observed disparities in pro-inflammatory and anti-inflammatory markers between PD patients and healthy individuals. This finding underscores the potential influence of immune system dysfunction in the genesis of this condition. A dysfunctional immune system can serve as a primary catalyst for systemic inflammation in the body, which may contribute to the emergence of various brain disorders. The identification of several genes associated with PD, as well as their connection to neuroinflammation, raises the likelihood of disease susceptibility. Moreover, advancing age and mitochondrial dysfunction can weaken the immune system, potentially implicating them in the onset of the disease, particularly among older individuals. Compromised integrity of the blood-brain barrier could facilitate the immune system's access to brain tissue. This exposure may lead to encounters with native antigens or infections, potentially triggering an autoimmune response. Furthermore, there is mounting evidence supporting the notion that gut dysbiosis might represent an initial trigger for brain inflammation, ultimately promoting neurodegeneration. In this comprehensive review, we will delve into the numerous hypotheses surrounding the role of both innate and adaptive immunity in PD.

Cardiac 123I-Metaiodobenzylguanidine (MIBG) Scintigraphy in Parkinson's Disease: A Comprehensive Review

Cardiac sympathetic denervation, as documented on 123I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy, is relatively sensitive and specific for distinguishing Parkinson's disease (PD) from other neurodegenerative causes of parkinsonism. The present study aims to comprehensively review the literature regarding the use of cardiac MIBG in PD. MIBG is an analog to norepinephrine. They share the same uptake, storage, and release mechanisms. An abnormal result in the cardiac MIBG uptake in individuals with parkinsonism can be an additional criterion for diagnosing PD. However, a normal result of cardiac MIBG in individuals with suspicious parkinsonian syndrome does not exclude the diagnosis of PD. The findings of cardiac MIBG studies contributed to elucidating the pathophysiology of PD. We investigated the sensitivity and specificity of cardiac MIBG scintigraphy in PD. A total of 54 studies with 3114 individuals diagnosed with PD were included. The data were described as means with a Hoehn and Yahr stage of 2.5 and early and delayed registration H/M ratios of 1.70 and 1.51, respectively. The mean cutoff for the early and delayed phases were 1.89 and 1.86. The sensitivity for the early and delayed phases was 0.81 and 0.83, respectively. The specificity for the early and delayed phases were 0.86 and 0.80, respectively.

Live cell in situ lysosomal GCase activity correlates to alpha-synuclein levels in human differentiated neurons with LRRK2 and GBA1 mutations

Introduction

Heterozygous mutations in GBA1, which encodes the lysosomal hydrolase glucocerebrosidase (GCase), are a common risk factor for the neurodegenerative movement disorder Parkinson's disease (PD). Consequently, therapeutic options targeting the GCase enzyme are in development. An important aspect of this development is determining the effect of potential modifying compounds on GCase activity, which can be complicated by the different methods and substrate probes that are commonly employed for this purpose.

Methods

In this study, we employed the GCase substrate probe 5-(pentafluorobenzoylamino)fluorescein di-D-glucopyranoside (PFB-FDGlu) in combination with live cell imaging to measure GCase activity in situ in the lysosome.

Results

The live cell assay was validated using the GCase inhibitor conduritol-B-epoxide and with GBA1 knockout neural cells and was then used to assess GCase activity in iPSC differentiated into neural stem cells and neurons that were obtained from idiopathic PD patients and PD patients with the LRRK2 G2019S and GBA N370S mutations, as well as controls (n = 4 per group). Heterogeneity in GCase activity was observed across all groups. However, a significant inverse correlation between GCase activity and levels of alpha-synuclein protein was observed.

Discussion

The live cell imaging assay for GCase activity could be useful for further understanding the role of GCase in PD and screening potential modifying compounds in differentiated human cell models.

GUCY2C signaling limits dopaminergic neuron vulnerability to toxic insults

Mitochondrial dysfunction and reactive oxygen species (ROS) accumulation within the substantia nigra pars compacta (SNpc) are central drivers of dopaminergic (DA) neuron death in Parkinson's disease (PD). Guanylyl cyclases, and their second messengers cyclic (c)GMP, support mitochondrial function, protecting against ROS and promoting cell survival in a number of tissues. However, the role of the guanylyl cyclase-cGMP axis in defining the vulnerability of DA neurons in the SNpc in PD remains unclear, in part due to the challenge of manipulating cGMP levels selectively in midbrain DA neurons. In that context, guanylyl cyclase C (GUCY2C), a receptor primarily expressed by intestinal epithelial cells, was discovered recently in midbrain DA neurons. Here, we demonstrate that GUCY2C promotes mitochondrial function, reducing oxidative stress and protecting DA neurons from degeneration in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of neurodegeneration. GUCY2C is overexpressed in the SNpc in PD patients and in mice treated with MPTP, possibly reflecting a protective response to oxidative stress. Moreover, cGMP signaling protects against oxidative stress, mitochondrial impairment, and cell death in cultured DA neurons. These observations reveal a previously unexpected role for the GUCY2C-cGMP signaling axis in controlling mitochondrial dysfunction and toxicity in nigral DA neurons, highlighting the therapeutic potential of targeting DA neuron GUCY2C to prevent neurodegeneration in PD.

Whole Transcriptome Analysis of Substantia Nigra in Mice with MPTP-Induced Parkinsonism Bearing Defective Glucocerebrosidase Activity

Mutations in the GBA1 gene represent the major genetic risk factor for Parkinson's disease (PD). The lysosomal enzyme beta-glucocerebrosidase (GCase) encoded by the GBA1 gene participates in both the endolysosomal pathway and the immune response. Disruption of these mechanisms is involved in PD pathogenesis. However, molecular mechanisms of PD associated with GBA1 mutations (GBA-PD) are unknown today in particular due to the partial penetrance of GBA1 variants in PD. The modifiers of GBA1 penetrance have not been elucidated. We characterized the transcriptomic profiles of cells from the substantia nigra (SN) of mice with co-injection with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and selective inhibitor of GCase activity (conduritol-β-epoxide, (CBE)) to mimic PD bearing GCase dysfunction (MPTP+CBE), mice treated with MPTP, mice treated with CBE and control mice treated with injection of sodium chloride (NaCl) (vehicle). Differential expression analysis, pathway enrichment analysis, and outlier detection were performed. Functional clustering of differentially represented transcripts revealed more processes associated with the functioning of neurogenesis, inflammation, apoptosis and autophagy in MPTP+CBE and MPTP mice than in vehicle mice, with a more pronounced alteration of autophagy processes in MPTP+CBE mice than in MPTP mice. The PI3K-Akt-mTOR signaling pathway may be considered a potential target for therapy in PD with GCase dysfunction.

Sex differences in alpha-synucleinopathies: a systematic review

Background

Past research indicates a higher prevalence, incidence, and severe clinical manifestations of alpha-synucleinopathies in men, leading to a suggestion of neuroprotective properties of female sex hormones (especially estrogen). The potential pathomechanisms of any such effect on alpha-synucleinopathies, however, are far from understood. With that aim, we undertook to systematically review, and to critically assess, contemporary evidence on sex and gender differences in alpha-synucleinopathies using a bench-to-bedside approach.

Methods

In this systematic review, studies investigating sex and gender differences in alpha-synucleinopathies (Rapid Eye Movement (REM) Behavior Disorder (RBD), Parkinson's Disease (PD), Dementia with Lewy Bodies (DLB), Multiple System Atrophy (MSA)) from 2012 to 2022 were identified using electronic database searches of PubMed, Embase and Ovid.

Results

One hundred sixty-two studies were included; 5 RBD, 6 MSA, 20 DLB and 131 PD studies. Overall, there is conclusive evidence to suggest sex-and gender-specific manifestation in demographics, biomarkers, genetics, clinical features, interventions, and quality of life in alpha-synucleinopathies. Only limited data exists on the effects of distinct sex hormones, with majority of studies concentrating on estrogen and its speculated neuroprotective effects.

Conclusion

Future studies disentangling the underlying sex-specific mechanisms of alpha-synucleinopathies are urgently needed in order to enable novel sex-specific therapeutics.

GBA Regulates EMT/MET and Chemoresistance in Squamous Cell Carcinoma Cells by Modulating the Cellular Glycosphingolipid Profile

Glycosphingolipids (GSL) are plasma membrane components that influence molecular processes involved in cancer initiation, progression, and therapeutic responses. They also modulate receptor tyrosine kinases involved in EMT. Therefore, understanding the mechanisms that regulate GSLs in cancer has important therapeutic potential. One critical regulator of GSLs is the lysosomal glucosylceramidase β1 (GBA) that catalyzes the last step in GSL degradation. We show that, in cancer, GBA copy number amplifications and increased expression are widespread. We show that depleting GBA in squamous cell carcinoma cell lines results in a mesenchymal-to-epithelial shift, decreased invasion and migration, increased chemotherapeutic sensitivity, and decreased activation of receptor tyrosine kinases that are involved in regulating EMT. Untargeted lipidomics shows that GBA depletion had significant effects on sphingolipids and GSLs, suggesting that increased GBA activity in cancer sustains EMT and chemoresistance by modulating receptor tyrosine kinase activity and signaling via effects on the cellular lipid profile.

Akkermansia muciniphila in neuropsychiatric disorders: friend or foe?

An accumulating body of evidence suggests that the bacterium Akkermansia muciniphila exhibits positive systemic effects on host health, mainly by improving immunological and metabolic functions, and it is therefore regarded as a promising potential probiotic. Recent clinical and preclinical studies have shown that A. muciniphila plays a vital role in a variety of neuropsychiatric disorders by influencing the host brain through the microbiota-gut-brain axis (MGBA). Numerous studies observed that A. muciniphila and its metabolic substances can effectively improve the symptoms of neuropsychiatric disorders by restoring the gut microbiota, reestablishing the integrity of the gut mucosal barrier, regulating host immunity, and modulating gut and neuroinflammation. However, A. muciniphila was also reported to participate in the development of neuropsychiatric disorders by aggravating inflammation and influencing mucus production. Therefore, the exact mechanism of action of A. muciniphila remains much controversial. This review summarizes the proposed roles and mechanisms of A. muciniphila in various neurological and psychiatric disorders such as depression, anxiety, Parkinson's disease, Alzheimer's disease, multiple sclerosis, strokes, and autism spectrum disorders, and provides insights into the potential therapeutic application of A. muciniphila for the treatment of these conditions.

Parkinson's disease in a patient with GBA and LRRK2 covariants after acute hypoxic insult: a case report

BACKGROUND

The glucocerebrosidase (GBA) and leucine-rich repeat kinase 2 (LRRK2) genes are associated with the risk of sporadic Parkinson's disease (PD). As an environmental factor, hypoxic insults may impair dopamine neurons in the substantia nigra and exacerbate PD symptoms. However, covariants of GBA and LRRK2 combined with hypoxic insults in clinical cases of Parkinsonism have not yet been reported.

CASE PRESENTATION

A 69-year-old male patient with PD and his relatives were clinically characterized and sequenced using the whole-exome technique. A novel covariant, c.1448 T > C (p. L483P, rs421016) on GBA and c.691 T > C (p. S231P, rs201332859) on LRRK2 were identified in this patient who first developed bradykinesia and rigidity in the neck at one month after an acute hypoxic insult during mountaineering. The patient presented with a mask-like face, festinating gait, asymmetric bradykinesia, and moderate rigidity. These symptoms were treated with levodopa and pramipexole, resulting in a 65% improvement in the Unified Parkinson's Disease Rating Scale (UPDRS) motor score. These parkinsonian symptoms persisted and developed with hallucinations, constipation, and rapid eye movement sleep behavior disorder. After 4 years, the patient exhibited a wearing-off phenomenon and died from pulmonary infection 8 years after disease onset. His parents, wife, and siblings were not diagnosed with PD, and his son carried p. L483P without Parkinsonism-like symptoms.

CONCLUSIONS

This is a case report of PD after hypoxic insult in a patient carrying a covariant of GBA and LRRK2. This study may help us understand the interaction between genetic and environmental factors in clinical PD.

Potential Binding Sites of Pharmacological Chaperone NCGC00241607 on Mutant β-Glucocerebrosidase and Its Efficacy on Patient-Derived Cell Cultures in Gaucher and Parkinson's Disease

Mutations in the GBA1 gene, encoding the lysosomal enzyme glucocerebrosidase (GCase), cause Gaucher disease (GD) and are the most common genetic risk factor for Parkinson's disease (PD). Pharmacological chaperones (PCs) are being developed as an alternative treatment approach for GD and PD. To date, NCGC00241607 (NCGC607) is one of the most promising PCs. Using molecular docking and molecular dynamics simulation we identified and characterized six allosteric binding sites on the GCase surface suitable for PCs. Two sites were energetically more preferable for NCGC607 and located nearby to the active site of the enzyme. We evaluated the effects of NCGC607 treatment on GCase activity and protein levels, glycolipids concentration in cultured macrophages from GD (n = 9) and GBA-PD (n = 5) patients as well as in induced human pluripotent stem cells (iPSC)-derived dopaminergic (DA) neurons from GBA-PD patient. The results showed that NCGC607 treatment increased GCase activity (by 1.3-fold) and protein levels (by 1.5-fold), decreased glycolipids concentration (by 4.0-fold) in cultured macrophages derived from GD patients and also enhanced GCase activity (by 1.5-fold) in cultured macrophages derived from GBA-PD patients with N370S mutation (p < 0.05). In iPSC-derived DA neurons from GBA-PD patients with N370S mutation NCGC607 treatment increased GCase activity and protein levels by 1.1-fold and 1.7-fold (p < 0.05). Thus, our results showed that NCGC607 could bind to allosteric sites on the GCase surface and confirmed its efficacy on cultured macrophages from GD and GBA-PD patients as well as on iPSC-derived DA neurons from GBA-PD patients.

A Phase 1B Trial in GBA1-Associated Parkinson's Disease of BIA-28-6156, a Glucocerebrosidase Activator

BACKGROUND

Loss-of-function mutations in the GBA1 gene are one of the most common genetic risk factors for onset of Parkinson's disease and subsequent progression (GBA-PD). GBA1 encodes the lysosomal enzyme glucocerebrosidase (GCase), a promising target for a possible first disease-modifying therapy. LTI-291 is an allosteric activator of GCase, which increases the activity of normal and mutant forms of GCase.

OBJECTIVES

This first-in-patient study evaluated the safety, tolerability, pharmacokinetics, and pharmacodynamics of 28 daily doses of LTI-291 in GBA-PD.

METHODS

This was a randomized, double-blind, placebo-controlled trial in 40 GBA-PD participants. Twenty-eight consecutive daily doses of 10, 30, or 60 mg of LTI-291 or placebo were administered (n = 10 per treatment allocation). Glycosphingolipid (glucosylceramide and lactosylceramide) levels were measured in peripheral blood mononuclear cells (PBMCs), plasma, and cerebrospinal fluid (CSF), and a test battery of neurocognitive tasks, the Movement Disorder Society-Unified Parkinson's Disease Rating Scale and the Mini-Mental State Exam, were performed.

RESULTS

LTI-291 was generally well tolerated, no deaths or treatment-related serious adverse events occurred, and no participants withdrew due to adverse events. C_max , and AUC_0-6 of LTI-291 increased in a dose-proportional manner, with free CSF concentrations equal to the free fraction in plasma. A treatment-related transient increase in intracellular glucosylceramide (GluCer) in PBMCs was measured.

CONCLUSION

These first-in-patient studies demonstrated that LTI-291 was well tolerated when administered orally for 28 consecutive days to patients with GBA-PD. Plasma and CSF concentrations that are considered pharmacologically active were reached (ie, sufficient to at least double GCase activity). Intracellular GluCer elevations were detected. Clinical benefit will be assessed in a larger long-term trial in GBA-PD. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

The Management of Parkinson's Disease: An Overview of the Current Advancements in Drug Delivery Systems

Parkinson's disease (PD) has significantly affected a large proportion of the elderly population worldwide. According to the World Health Organization, approximately 8.5 million people worldwide are living with PD. In the United States, an estimated one million people are living with PD, with approximately 60,000 new cases diagnosed every year. Conventional therapies available for Parkinson's disease are associated with limitations such as the wearing-off effect, on-off period, episodes of motor freezing, and dyskinesia. In this review, a comprehensive overview of the latest advances in DDSs used to reduce the limitations of current therapies will be presented, and both their promising features and drawbacks will be discussed. We are also particularly interested in the technical properties, mechanism, and release patterns of incorporated drugs, as well as nanoscale delivery strategies to overcome the blood-brain barrier.

Glucocerebrosidase activity and lipid levels are related to protein pathologies in Parkinson's disease

Parkinson's disease (PD) and dementia with Lewy bodies (DLB) are progressive neurodegenerative diseases characterized by the accumulation of misfolded α-synuclein in the form of Lewy pathology. While most cases are sporadic, there are rare genetic mutations that cause disease and more common variants that increase incidence of disease. The most prominent genetic mutations for PD and DLB are in the GBA1 and LRRK2 genes. GBA1 mutations are associated with decreased glucocerebrosidase activity and lysosomal accumulation of its lipid substrates, glucosylceramide and glucosylsphingosine. Previous studies have shown a link between this enzyme and lipids even in sporadic PD. However, it is unclear how the protein pathologies of disease are related to enzyme activity and glycosphingolipid levels. To address this gap in knowledge, we examined quantitative protein pathology, glucocerebrosidase activity and lipid substrates in parallel from 4 regions of 91 brains with no neurological disease, idiopathic, GBA1-linked, or LRRK2-linked PD and DLB. We find that several biomarkers are altered with respect to mutation and progression to dementia. We found mild association of glucocerebrosidase activity with disease, but a strong association of glucosylsphingosine with α-synuclein pathology, irrespective of genetic mutation. This association suggests that Lewy pathology precipitates changes in lipid levels related to progression to dementia.