Parkinson disease

Exploring the versatility of Drosophila melanogaster as a model organism in biomedical research: a comprehensive review

Drosophila melanogaster is a highly versatile model organism that has profoundly advanced our understanding of human diseases. With more than 60% of its genes having human homologs, Drosophila provides an invaluable system for modelling a wide range of pathologies, including neurodegenerative disorders, cancer, metabolic diseases, as well as cardiac and muscular conditions. This review highlights key developments in utilizing Drosophila for disease modelling, emphasizing the genetic tools that have transformed research in this field. Technologies such as the GAL4/UAS system, RNA interference (RNAi) and CRISPR-Cas9 have enabled precise genetic manipulation, with CRISPR-Cas9 allowing for the introduction of human disease mutations into orthologous Drosophila genes. These approaches have yielded critical insights into disease mechanisms, identified novel therapeutic targets and facilitated both drug screening and toxicological studies. Articles were selected based on their relevance, impact and contribution to the field, with a particular focus on studies offering innovative perspectives on disease mechanisms or therapeutic strategies. Our findings emphasize the central role of Drosophila in studying complex human diseases, underscoring its genetic similarities to humans and its effectiveness in modelling conditions such as Alzheimer's disease, Parkinson's disease and cancer. This review reaffirms Drosophila's critical role as a model organism, highlighting its potential to drive future research and therapeutic advancements.

Unraveling brain aging through the lens of oral microbiota

The oral cavity is a complex physiological community encompassing a wide range of microorganisms. Dysbiosis of oral microbiota can lead to various oral infectious diseases, such as periodontitis and tooth decay, and even affect systemic health, including brain aging and neurodegenerative diseases. Recent studies have highlighted how oral microbes might be involved in brain aging and neurodegeneration, indicating potential avenues for intervention strategies. In this review, we summarize clinical evidence demonstrating a link between oral microbes/oral infectious diseases and brain aging/neurodegenerative diseases, and dissect potential mechanisms by which oral microbes contribute to brain aging and neurodegeneration. We also highlight advances in therapeutic development grounded in the realm of oral microbes, with the goal of advancing brain health and promoting healthy aging.

Liposomes as versatile agents for the management of traumatic and nontraumatic central nervous system disorders: drug stability, targeting efficiency, and safety

Various nanoparticle-based drug delivery systems for the treatment of neurological disorders have been widely studied. However, their inability to cross the blood-brain barrier hampers the clinical translation of these therapeutic strategies. Liposomes are nanoparticles composed of lipid bilayers, which can effectively encapsulate drugs and improve drug delivery across the blood-brain barrier and into brain tissue through their targeting and permeability. Therefore, they can potentially treat traumatic and nontraumatic central nervous system diseases. In this review, we outlined the common properties and preparation methods of liposomes, including thin-film hydration, reverse-phase evaporation, solvent injection techniques, detergent removal methods, and microfluidics techniques. Afterwards, we comprehensively discussed the current applications of liposomes in central nervous system diseases, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, traumatic brain injury, spinal cord injury, and brain tumors. Most studies related to liposomes are still in the laboratory stage and have not yet entered clinical trials. Additionally, their application as drug delivery systems in clinical practice faces challenges such as drug stability, targeting efficiency, and safety. Therefore, we proposed development strategies related to liposomes to further promote their development in neurological disease research.

Salsolinol as an RNA m6A methylation inducer mediates dopaminergic neuronal death by regulating YAP1 and autophagy

JOURNAL/nrgr/04.03/01300535-202503000-00032/figure1/v/2024-06-17T092413Z/r/image-tiff Salsolinol (1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline, Sal) is a catechol isoquinoline that causes neurotoxicity and shares structural similarity with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, an environmental toxin that causes Parkinson's disease. However, the mechanism by which Sal mediates dopaminergic neuronal death remains unclear. In this study, we found that Sal significantly enhanced the global level of N6-methyladenosine (m6A) RNA methylation in PC12 cells, mainly by inducing the downregulation of the expression of m6A demethylases fat mass and obesity-associated protein (FTO) and alkB homolog 5 (ALKBH5). RNA sequencing analysis showed that Sal downregulated the Hippo signaling pathway. The m6A reader YTH domain-containing family protein 2 (YTHDF2) promoted the degradation of m6A-containing Yes-associated protein 1 (YAP1) mRNA, which is a downstream key effector in the Hippo signaling pathway. Additionally, downregulation of YAP1 promoted autophagy, indicating that the mutual regulation between YAP1 and autophagy can lead to neurotoxicity. These findings reveal the role of Sal on m6A RNA methylation and suggest that Sal may act as an RNA methylation inducer mediating dopaminergic neuronal death through YAP1 and autophagy. Our results provide greater insights into the neurotoxic effects of catechol isoquinolines compared with other studies and may be a reference for assessing the involvement of RNA methylation in the pathogenesis of Parkinson's disease.

Role of copper chelating agents: between old applications and new perspectives in neuroscience

The role of copper element has been an increasingly relevant topic in recent years in the fields of human and animal health, for both the study of new drugs and innovative food and feed supplements. This metal plays an important role in the central nervous system, where it is associated with glutamatergic signaling, and it is widely involved in inflammatory processes. Thus, diseases involving copper (II) dyshomeostasis often have neurological symptoms, as exemplified by Alzheimer's and other diseases (such as Parkinson's and Wilson's diseases). Moreover, imbalanced copper ion concentrations have also been associated with diabetes and certain types of cancer, including glioma. In this paper, we propose a comprehensive overview of recent results that show the importance of these metal ions in several pathologies, mainly Alzheimer's disease, through the lens of the development and use of copper chelators as research compounds and potential therapeutics if included in multi-target hybrid drugs. Seeing how copper homeostasis is important for the well-being of animals as well as humans, we shortly describe the state of the art regarding the effects of copper and its chelators in agriculture, livestock rearing, and aquaculture, as ingredients for the formulation of feed supplements as well as to prevent the effects of pollution on animal productions.

Mitochondrial DAMPs: Key mediators in neuroinflammation and neurodegenerative disease pathogenesis

Neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and amyotrophic lateral sclerosis (ALS) are increasingly linked to mitochondrial dysfunction and neuroinflammation. Central to this link are mitochondrial damage-associated molecular patterns (mtDAMPs), including mitochondrial DNA, ATP, and reactive oxygen species, released during mitochondrial stress or damage. These mtDAMPs activate inflammatory pathways, such as the NLRP3 inflammasome and cGAS-STING, contributing to the progression of neurodegenerative diseases. This review delves into the mechanisms by which mtDAMPs drive neuroinflammation and discusses potential therapeutic strategies targeting these pathways to mitigate neurodegeneration. Additionally, it explores the cross-talk between mitochondria and the immune system, highlighting the complex interplay that exacerbates neuronal damage. Understanding the role of mtDAMPs could pave the way for novel treatments aimed at modulating neuroinflammation and slowing disease progression, ultimately improving patient outcome.

Antibiotic Exposure and Risk of Parkinson Disease in South Korea: A Nationally Representative Retrospective Cohort Study

Background and Objectives

Recent studies have suggested that antibiotics could be a contributing factor to Parkinson disease (PD), but validation in other population cohorts, such as Asians, is needed. This study examined the association between exposure to antibiotics and PD risk in the Korean population.

Methods

Using the National Health Insurance Service (NHIS) database, this population-level cohort research study from Korea included 298,379 people aged 40 years and older who underwent a national health examination in 2004-2005. Cumulative antibiotic exposure days were investigated over 4 years (2002-2005), and new cases of PD were followed for 14 years (2006-2019). Various covariates, such as infectious diseases, were considered in the analysis. Multivariable Cox proportional hazards regression was used to calculate adjusted hazard ratios (aHRs) and CIs for the PD risk from antibiotic exposure.

Results

PD risk was statistically significantly higher in those exposed to antibiotics for ≥121 days than in those not exposed to antibiotics (aHR, 1.29; 95% CI 1.07-1.55). In addition, compared with those exposed to antibiotics for 1-14 days, those exposed to antibiotics for ≥121 days had a higher risk of PD (aHR, 1.37; 95% CI 1.17-1.61). The results of sensitivity analyses that applied washout periods or extended antibiotic exposure periods were consistent with those of the main analyses.

Discussion

Extended usage of antibiotics was linked to a higher incidence of PD, even after controlling for several risk variables. Further research is needed to warrant the causation and mechanisms of antibiotic exposure and PD.

Potential role of long noncoding RNA maternally expressed gene 3 (MEG3) in the process of neurodegeneration

Neurodegenerative diseases (ND) are complex diseases of still unknown etiology. Lately, long non-coding RNAs (lncRNAs) have become increasingly popular and implicated in several pathologies as they have several roles and appear to be involved in all biological processes such as cell signaling and cycle control as well as translation and transcription. MEG3 is one of these and acts by binding proteins or directly or competitively binding miRNAs. It has a crucial role in controlling cell death, inflammatory process, oxidative stress, endoplasmic reticulum stress, epithelial-mesenchymal transition and other processes. Recent reports showed that MEG3 is a major driving force of the necrosis phenomena in AD, causing the death of neurons, and its upregulation in cancer patients was linked to tumor suppression. Dysregulation of MEG3 affects neuronal cell death, inflammatory process, smooth muscle cell proliferation and consequently leads to the initiation or the acceleration of the disease. This review examines the current state of knowledge concerning the level of expression and the regulatory function of MEG3 in relation to several NDs. In addition, we examined the relation of MEG3 with neurotrophic factors such as Tumor growth factor β (TGFβ) and its possible mechanism of action. A comprehensive and in-depth analysis of the role of MEG3 in ND could give a clearer picture about the initiation of the process of neuronal death and help develop an alternative therapy that targets MEG3.

Prevalence and associations of self-reported sleep problems in a large sample of patients with Parkinson's disease

Sleep problems are important comorbid features of, and risk factors for, neurodegenerative diseases such as Parkinson's disease (PD). To assess the prevalence and associations of sleep problems in patients with PD we analysed data from almost 54,000 participants in the Fox Insight study, including data from 38,588 patients with PD. Sleep problems are common in PD, with ~84% of respondents with PD reporting difficulty falling or staying asleep. Experiences of insomnia, restless leg syndrome, vivid dreams, acting out dreams, and the use of sleep medication are over-represented in patients with PD compared with matched healthy controls. Male sex and PD onset before the age of 50 were also associated with a greater risk of sleep problems. A physician diagnosis of insomnia was associated with more symptoms of depression, impairment of cognition-dependent independence, and a lower quality of life. Sleep problems were also associated with a higher prevalence of OFF periods compared with PD patients without sleep problems. 6.7% of PD patients endorsed sleep complaints as their most bothersome symptom, and reported non-specific poor sleep quality as the most common sleep problem. These patients also had a better quality of life and lower depression and cognitive impairments than patients for whom postural instability was their most bothersome symptom, indicating the relative burden of sleep problems is contextualised by the severity of motor symptoms. Overall, these findings reinforce the high prevalence of sleep problems in a very large sample of PD patients, and indicate important associations of sleep problems with daily function and quality of life in PD.

A nanoparticle-based wireless deep brain stimulation system that reverses Parkinson's disease

Deep brain stimulation technology enables the neural modulation with precise spatial control but requires permanent implantation of conduits. Here, we describe a photothermal wireless deep brain stimulation nanosystem capable of eliminating α-synuclein aggregates and restoring degenerated dopamine neurons in the substantia nigra to treat Parkinson's disease. This nanosystem (ATB NPs) consists of gold nanoshell, an antibody against the heat-sensitive transient receptor potential vanilloid family member 1 (TRPV1), and β-synuclein (β-syn) peptides with a near infrared-responsive linker. ATB NPs by stereotactic injection target dopamine neurons expressing TRPV1 receptors in the substantia nigra. Upon pulsed near-infrared irradiation, ATB NPs, serving as nanoantennae, convert the light into heat, leading to calcium ion influx, depolarization, and action potentials in dopamine neurons through TRPV1 receptors. Simultaneously, β-synuclein peptides released from ATB NPs cooperate with chaperone-mediated autophagy initiated by heat shock protein, HSC70, to effectively eliminate α-synuclein fibrils in neurons. These orchestrated actions restored pathological dopamine neurons and locomotor behaviors of Parkinson's disease.

Network-Based Drug Optimization toward the Treatment of Parkinson's Disease: NRF2, MAO-B, Oxidative Stress, and Chronic Neuroinflammation

Parkinson's disease (PD), the second most common neurodegenerative disorder, affects around 10 million people worldwide. It is a multifactorial disease marked by dopaminergic neuron loss with oxidative stress (OS) and neuroinflammation as key pathological drivers. Current treatments focus on dopamine replacement and are symptomatic, underscoring the urgent need for disease-modifying therapies. Here, we present a novel class of dual MAO-B inhibitors and NRF2 inducers with neuroprotective properties in in vitro PD models. Through an optimization program, we enhanced their MAO-B inhibitory potency, selectivity, and NRF2 induction capacity while achieving favorable pharmacokinetic profiles. Virtual library screening identified two core derivatives, leading to the development of compound 11, which exhibited potent anti-inflammatory and neuroprotective activity in OS-related in vitro models. Compound 11 also demonstrated high liver microsomal stability and favorable pharmacokinetics in mice, making it a promising candidate for further investigation as a potential PD therapy.

Infiltrating peripheral monocyte TREM-1 mediates dopaminergic neuron injury in substantia nigra of Parkinson's disease model mice

Neuroinflammation is a key factor in the pathogenesis of Parkinson's disease (PD). Activated microglia in the central nervous system (CNS) and infiltration of peripheral immune cells contribute to dopaminergic neuron loss. However, the role of peripheral immune responses, particularly triggering receptor expressed on myeloid cells-1 (TREM-1), in PD remains unclear. Using a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine hydrochloride (MPTP)-induced PD mouse model, we examined TREM-1 expression and monocyte infiltration in the substantia nigra pars compacta (SNpc). We found that MPTP increased peripheral monocytes, and deletion of peripheral monocytes protected against MPTP neurotoxicity in the SNpc. TREM-1 inhibition, both genetically and pharmacologically, reduced monocyte infiltration, alleviated neuroinflammation, and preserved dopaminergic neurons, resulting in improved motor function. Furthermore, adoptive transfer of TREM-1-expressing monocytes from PD model mice to naive mice induced neuronal damage and motor deficits. These results underscore the critical role of peripheral monocytes and TREM-1 in PD progression, suggesting that targeting TREM-1 could be a promising therapeutic approach to prevent dopaminergic neurodegeneration and motor dysfunction in PD. Schematic diagram of monocyte TREM-1-mediated dopaminergic neuron damage. The figure illustrates that in experimental MPTP-induced PD model mice, the number of inflammatory monocytes in the peripheral blood increases, after which the monocytes infiltrate the CNS through the Blood-Brain Barrier(BBB). These infiltrating monocytes increase the release of inflammatory cytokines and eventually cause neuronal injury. TREM-1 gene deletion and pharmacological blockade limit inflammatory monocyte recruitment into the SNpc and ameliorate neuroinflammatory events and the loss of dopaminergic neurons.

Sigma 1 Receptor and Its Pivotal Role in Neurological Disorders

Sigma 1 receptor (S1R) is a multifunctional, ligand-activated protein located in the membranes of the endoplasmic reticulum (ER). It mediates a variety of neurological disorders, including epilepsy, amyotrophic lateral sclerosis, Alzheimer's disease, Huntington's disease. The wide neuroprotective effects of S1R agonists are achieved by a variety of pro-survival and antiapoptotic S1R-mediated signaling functions. Nonetheless, relatively little is known about the specific molecular mechanisms underlying S1R activity. Many studies on S1R protein have highlighted the importance of maintaining normal cellular homeostasis through its control of calcium and lipid exchange between the ER and mitochondria, ER-stress response, and many other mechanisms. In this review, we will discuss S1R different cellular localization and explain S1R-associated biological activity, such as its localization in the ER-plasma membrane and Mitochondrion-Associated ER Membrane interfaces. While outlining the cellular mechanisms and important binding partners involved in these processes, we also explained how the dysregulation of these pathways contributes to neurodegenerative disorders.

Gynostemma pentaphyllum extract ameliorates motor dysfunc-tion in mouse Parkinsons disease model through inhibiting neuronal apoptosis

OBJECTIVES

To investigate the protective effects and underlying mechanisms of Gynostemma pentaphyllum extract on motor dysfunction in mouse model of Parkinson's disease (PD).

METHODS

Eighty C57BL/6 male mice were randomly divided into five groups: control group, PD model group, levodopa treatment group (positive control group), low-dose GP treatment group (LD-GP group), and high-dose GP treatment group (HD-GP group), with 16 mice per group. The PD model was induced by injection of 6-hydroxydopamine into the substantia nigra pars reticulata in mice of last 5 groups. Two weeks after 6-hydroxydopamine modeling, mice in positive control group received introperitoneal injection of levodopa 10 mg·kg－1·d－1, mice in LD-GP and HD-GP groups received oral 100 mg·kg－1·d－1 or 200 mg·kg－1·d－1 for 3 weeks, respectively. After 3-week-treatment, the effects of GP on motor dysfunction in 6-OHDA-induced PD mice were assessed using open field and CatWalk gait tests, while the effects on muscle strength were evaluated by forelimb grip strength. Immunofluorescence staining was used to detect the number of tyrosine hydroxylase (TH) positive neurons. The levels of dopamine and serotonin in midbrain were determined by enzyme-linked immunosorbent assay. In addition, Western blotting was performed to detect the expression of mitogen-activated protein kinase (MAPK) family proteins such as p- extracellular signal-regulated kinase (ERK)1/2, p-p38 and p-c-Jun N-terminal kinase (JNK)1/2 , and mitochondrial apoptosis pathway proteins such as B-cell lymphoma (Bcl)-2, Bcl-2 associated X protein (Bax), and cleaved- cysteine aspartic acid specific protease (caspase)-3.

RESULTS

Behavioral experiments showed that GP significantly improved the spontaneous activity and motor coordination of PD mice (P<0.05). And the forelimb grip strength was also increased by GP treatment (P<0.05), compared with PD model group. In addition, compared with model group, the number of TH-positive neurons in substantia nigra pars reticulata region, the levels of dopamine and serotonin in midbrain and the expression of p-ERK1/2 were significantly increased by GP treatment (all P<0.05), whereas the expression of p-p38 and p-JNK1/2, the ratio of Bax/Bcl-2 and cleaved-caspase 3/caspase 3 were significantly decreased (all P<0.05).

CONCLUSIONS

The results indicate that GP might increase dopamine and serotonin levels in midbrain and promoted the survival of dopaminergic neurons in substantia nigra pars reticulata by regulating the expression of phosphorylation of MAPK family proteins and the expression of mitochondrial apoptosis-related proteins, and then ameliorate motor deficits in PD mice.

Causal Association Between Cerebrospinal Fluid Metabolites and Parkinson's Disease: A Two-Sample Bidirectional Mendelian Randomization Study

OBJECTIVE

Observational studies suggest CSF metabolites may be linked to Parkinson's disease (PD) onset, but causality is uncertain. This study uses a two-sample bidirectional Mendelian randomization approach to investigate the causal relationship between CSF metabolites and PD.

METHODS

Data on 338 CSF metabolites and PD-related traits were obtained from genome-wide association studies (GWAS). Causal relationships between CSF metabolites and PD were assessed using inverse variance-weighted (IVW), MR-Egger regression, weighted median method, simple mode, and weighted mode. Sensitivity analyses for heterogeneity and pleiotropy were conducted to explore the robustness of the results.

RESULTS

Our analysis identified an association between nine CSF metabolites and PD. Notably, significant increases in the risk of PD were observed for Ribitol (IVW, OR: 1.45; 95% CI: 1.09-1.91; P=9.04×E-03), Lysine (IVW, OR: 1.54; 95% CI: 1.09-2.17; P=1.24×E-02), and O-sulfo-l-tyrosine (IVW, OR: 1.38; 95% CI: 1.06-1.79; P=1.60×E-02). Additionally, we found that elevated levels of oxidized cysteinyl-glycine and 1,5-anhydroglucitol were associated with a decreased risk of PD. Furthermore, PD was associated with alterations in 12 CSF metabolites, including significant increases in Acetoacetate (IVW, OR: 1.15; 95% CI: 1.02-1.30; P=1.79×E-02), S-methylcysteine (IVW, OR: 1.14; 95% CI: 1.02-1.29; P=2.62×E-02), and N-acetyl-3-methylhistidine (IVW, OR: 1.12; 95% CI: 1.01-1.23; P=2.22×E-02).

CONCLUSION

The identified CSF metabolites may serve as potential CSF metabolic biomarkers for screening and preventing PD in clinical practice and could also be considered as candidate molecules for future mechanistic exploration and drug target selection.

The Interplay Between Stigma and Asian Cultural Values in People with Parkinson's Disease and Their Caregivers

Parkinson's Disease (PD), the second most prevalent neurodegenerative disorder globally, often carries stigma for those affected; however, stigma's impact on PD caregivers is not well understood. This study investigates PD stigma and its interplay with cultural values, as well as explores the role of depressive symptomatology in shaping help-seeking attitudes among individuals with PD and the provision of support by PD caregivers. Using cross-sectional data collected from people living with PD and their caregivers, this study examines how adherence to Asian values influences the link between self-stigma and help-seeking tendencies in PD patients, as well as how affiliate stigma is linked to caregivers' willingness to help. Further, the mediational role of depression was explored. Among Chinese Parkinson's Disease (PD) patients, stronger adherence to Asian values heightens the negative effect of self-stigma on help-seeking from both professional and non-professional sources, with this process mediated by levels of depression. Similarly, caregivers exhibit the influence of affiliate stigma on help provision, which is accentuated by a higher adherence to Asian values; however, depression was not found to be a significant mediator in this context. This study underscores the need for culturally sensitive interventions tailored to Asian PD-affected families, highlighting its significance in both patient and caregiver contexts.

Advancing Parkinson's diagnosis: seed amplification assay for α-synuclein detection in minimally invasive samples

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by tremor, rigidity, and bradykinesia, beginning with early loss of dopaminergic neurons in the ventrolateral substantia nigra and advancing to broader neurodegeneration in the midbrain. The clinical heterogeneity of PD and the lack of specific diagnostic tests present significant challenges, highlighting the need for reliable biomarkers for early diagnosis. Alpha-synuclein (α-Syn), a protein aggregating into Lewy bodies and neurites in PD patients, has emerged as a key biomarker due to its central role in PD pathophysiology and potential to reflect pathological processes. Additionally, α-Syn allows earlier differentiation between PD and other neurodegenerative disorders with similar symptoms. Currently, detection of α-Syn pathology in post-mortem brain tissue remains the primary means of achieving a conclusive diagnosis, often revealing significant misdiagnoses. Seed amplification assay (SAA), initially developed for prion diseases, has been adapted to detect α-Syn aggregates in cerebrospinal fluid, showing promise for early diagnosis. Recent studies have demonstrated that SAA can also detect α-Syn aggregates in peripheral samples collected via minimally invasive procedures, such as skin, olfactory mucosa, saliva, and blood. However, the lack of standardized protocols limits clinical application. Standardizing protocols is essential to improve assay reliability and enable accurate patient identification for emerging therapies. This review examines studies on SAA for detecting α-Syn aggregates in minimally invasive samples, focusing on sample collection, processing, and reaction conditions.

Association of real life postural transitions kinematics with fatigue in neurodegenerative and immune diseases

Fatigue is prevalent in immune-mediated inflammatory and neurodegenerative diseases, yet its assessment relies largely on patient-reported outcomes, which capture perception but not fluctuations over time. Wearable sensors, like inertial measurement units (IMUs), offer a way to monitor daily activities and evaluate functional capacity. This study investigates the relationship between sit-to-stand and stand-to-sit transitions and self-reported physical and mental fatigue in participants with Parkinson's, Huntington's, rheumatoid arthritis, systemic lupus erythematosus, primary Sjögren's syndrome and inflammatory bowel disease. Over 4 weeks, participants wore an IMU and reported fatigue levels four times daily. Using mixed-effects models, associations were identified between fatigue and specific kinematic features, such as 5th and 95th percentiles of sit-to-stand performance, suggesting that fatigue alters the control and effort of movement. These kinematic features show promise as indicators for fatigue in these patient populations.

Genetic mutations in kinases: a comprehensive review on marketed inhibitors and unexplored targets in Parkinson's disease

This comprehensive review navigates the landscape of genetic mutations in kinases, offering a thorough examination of both marketed inhibitors and unexplored targets in the context of Parkinson's Disease (PD). Although existing treatments for PD primarily center on symptom management, progress in comprehending the molecular foundations of the disease has opened avenues for targeted therapeutic approaches. This review encompasses an in-depth analysis of four key kinases-PINK1, LRRK2, GAK, and PRKRA-revealing that LRRK2 has garnered the most attention with a plethora of marketed inhibitors. However, the study underscores notable gaps in the exploration of inhibitors for PINK1, GAK, and a complete absence for PRKRA. The observed scarcity of inhibitors for these kinases emphasizes a significant area of untapped potential in PD therapeutics. By drawing attention to these unexplored targets, the review highlights the urgent need for focused research and drug development efforts to diversify the therapeutic landscape, potentially providing novel interventions for halting or slowing the progression of PD.

The Dual Role of Survival Genes in Neurons and Cancer Cells: a Strategic Clinical Application of DX2 in Neurodegenerative Diseases and Cancer

In cancer cells, survival genes contribute to uncontrolled growth and the survival of malignant cells, leading to tumor progression. Neurons are post-mitotic cells, fully differentiated and non-dividing after neurogenesis and survival genes are essential for cellular longevity and proper functioning of the nervous system. This review explores recent research findings regarding the role of survival genes, particularly DX2, in degenerative neuronal tissue cells and cancer cells. Survival gene DX2, an exon 2-deleted splice variant of AIMP2 (aminoacyl-tRNA synthetase-interacting multi-functional protein 2), was found to be overexpressed in various cancer types. The potential of DX2 inhibitors as an anti-cancer drug arises from its unique ability to interact with various oncoproteins, such as KRAS and HSP70. Meanwhile, AIMP2 has been reported as a multifunctional cell death-inducing gene, and survival gene DX2 directly and indirectly inhibits AIMP2-induced cell death. DX2 plays multifaceted survival roles in degenerating neurons via various signaling pathways, including PARP 1, TRAF2, and p53 pathways. It is noteworthy that genes that were previously classified as oncogenes, such as AKT and XBP1, are now being considered as curative transgenes for targeting neurodegenerative diseases. A strategic direction for clinical application of survival genes in neurodegenerative disease and in cancer is justified.

An efficient ranking-based ensembled multiclassifier for neurodegenerative diseases classification using deep learning

Neurodegenerative diseases are group of debilitating and progressive disorders that primarily affect the structure and functions of nervous system, leading to gradual loss of neurons and subsequent decline in cognitive, and behavioral activities. The two frequent diseases affecting the world's significant population falling in the above category are Alzheimer's disease (AD) and Parkinson's disease (PD). These disorders substantially impact the quality of life and burden healthcare systems and society. The demographic characteristics, and machine learning approaches have now been employed to diagnose these illnesses; however, they possess accuracy limitations. Therefore, the authors have developed ranking-based ensemble approach based on the weighted strategy of deep learning classifiers. The whole modeling procedure of the proposed approach incorporates three phases. In phase I, preprocessing techniques are applied to clean the noise in datasets to make it standardized according to deep learning models as it significantly impacts their performance. In phase II, five deep learning models are selected for classification and calculation of prediction results. In phase III, a ranking-based ensemble approach is proposed to ensemble the results of the five models after calculating the ranks and weights of them. In addition, the Magnetic Resonance Imaging (MRI) datasets named Alzheimer's Disease Neuroimaging Initiative (ADNI) for AD classification and Parkinson's Progressive Marker Initiative (PPMI) for PD classification are selected to validate the proposed approach. Furthermore, the proposed method achieved the classification accuracy on AD- Cognitive Normals (CN) at 97.89%, AD- Mild Cognitive Impairment (MCI) at 99.33% and CN-MCI at 99.44% and on PD-CN at 99.22%, PD- Scans Without Evidence of Dopaminergic Effect (SWEDD) at 97.56% and CN-SWEDD at 98.22% respectively. Also, the multi-class classification shows the promising accuracy of 97.18% for AD and 97.85% for PD for the proposed framework. The findings of the study show that the proposed deep learning-based ensemble technique is competitive for AD and PD prediction in both multiclass and binary class classification. Furthermore, the proposed approach enhances generalization performance in diagnosing neurodegenerative diseases and performs better than existing approaches.

Wnt/β-catenin Signaling in Central Nervous System Regeneration

The Wnt/β-catenin signaling pathway plays a pivotal role in the development, maintenance, and repair of the central nervous system (CNS). This chapter explores the diverse functions of Wnt/β-catenin signaling, from its critical involvement in embryonic CNS development to its reparative and plasticity-inducing roles in response to CNS injury. We discuss how Wnt/β-catenin signaling influences various CNS cell types-astrocytes, microglia, neurons, and oligodendrocytes-each contributing to repair and plasticity after injury. The chapter also addresses the pathway's involvement in CNS disorders such as Alzheimer's and Parkinson's diseases, psychiatric disorders, and traumatic brain injury (TBI), highlighting potential Wnt-based therapeutic approaches. Lastly, zebrafish are presented as a promising model organism for studying CNS regeneration and neurodegenerative diseases, offering insights into future research and therapeutic development.

Impact of Parkinson Medication on Neuropsychiatric and Neurocognitive Symptoms in Patients with Advanced Parkinson Disease Prior to Deep Brain Stimulation

INTRODUCTION

This study evaluates the impact of Parkinson disease (PD) medication in advanced PD on neuropsychological performance, psychiatric symptoms, impulsivity and the quality of life. In the 4-year period 27 patients with advanced PD, scheduled for deep brain stimulation (DBS) surgery (N=27, mean age: 58.9±7.1, disease duration: 10.0 years±4.2) were examined preoperatively. We hypothesized that a high dosage of PD medication or current use of dopamine agonists affect cognitive functioning and psychiatric wellbeing.

METHODS

We performed two subgroup analyses with low versus high levodopa-equivalent Dosage (LED) medication and without versus with dopaminagonistic medication.

RESULTS

The neuropsychological testing revealed significant differences in the verbal learn- and memory-test (VLMT) during the learning passage (U=36.500, Z=- 2.475, p=0.012) and in the subtest of the semantic fluency of Regensburg verbal fluency test (RWT) (t(25)=- 2.066, p=0.049) with better results for patients without dopaminagonistic medication. Pearson correlation analyses of LED in correlation with the clinical and cognitive dependent variables showed a significant higher PANSS total score in patients with higher LED medication (r=0.491, p=0.009). In addition, lower LED treatment was associated with significant higher scores in the impulsivity perseverance subtest (r=- 0.509, p=0.008).

DISCUSSION

In conclusion, we found lower LEDs to be correlated with a better perseverance in the impulsivity test and additional treatment with a dopamine agonist influenced some verbal learning tasks and the PANSS total score in patients with advanced PD. This should be considered prior to DBS surgery.

Olfactory Network Disruptions as Mediators of Cognitive Impairment in De Novo Parkinson's Disease

OBJECTIVES

Parkinson's disease (PD) is characterized by olfactory dysfunction (OD) and cognitive deficits at its early stages, yet the link between OD and cognitive deficits is also not well-understood. This study aims to examine the changes in the olfactory network associated with OD and their relationship with cognitive function in de novo PD patients.

METHODS

A total of 116 drug-naïve PD patients and 51 healthy controls (HCs) were recruited for this study. Graph theoretical approaches were employed to reveal the abnormalities of topological characteristics in the olfactory network. Network-based statistics (NBS) analysis was employed to identify the abnormal subnetworks within the olfactory network. Moreover, partial correlation analysis and mediation analysis were performed to examine the relationship between the abnormal network metrics, olfactory function, and cognitive function.

RESULTS

Graph theoretical approaches revealed reduced betweenness centrality of the left insula in PD patients with OD. NBS analysis identified a disrupted subnetwork with decreased functional connectivity, primarily involving limbic regions. The average functional connectivity of this subnetwork partially mediated the relationship between olfactory and cognitive performance. Higher-granularity network analysis further highlighted the insula's key role and revealed reduced efficiency of information integration within the olfactory network.

CONCLUSIONS

OD was associated with specific changes in the functional olfactory network, which, in turn, affects cognitive function. These findings underscore the importance of assessing and addressing OD. Understanding the neural correlates of OD could provide novel insights into the management and comprehension of cognitive impairment in PD.

Novel Gene Therapy Approaches for Targeting Neurodegenerative Disorders: Focusing on Delivering Neurotrophic Genes

Neurodegenerative illnesses (NDDs) like Alzheimer's, Parkinson's, amyotrophic lateral sclerosis, spinal muscular atrophy, and Huntington's disease have demonstrated considerable potential for gene therapy as a viable therapeutic intervention. NDDs are marked by the decline of neurons, resulting in changes in both behavior and pathology within the body. Strikingly, only symptomatic management is available without a cure for the NDDs. There is an unmet need for a permanent therapeutic approach. Many studies have been going on to target the newer therapeutic molecular targets for NDDs including gene-based therapy. Gene therapy has the potential to provide therapeutic benefits to a large number of patients with NDDs by offering mechanisms including neuroprotection, neuro-restoration, and rectification of pathogenic pathways. Gene therapy is a medical approach that aims to modify the biological characteristics of living cells by controlling the expression of specific genes in certain neurological disorders. Despite being the most complex and well-protected organ in the human body, there is clinical evidence to show that it is possible to specifically target the central nervous system (CNS). This provides hope for the prospective application of gene therapy in treating NDDs in the future. There are several advanced techniques available for using viral or non-viral vectors to deliver the therapeutic gene to the afflicted region. Neurotrophic factors (NTF) in the brain are crucial for the development, differentiation, and survival of neurons in the CNS, making them important in the context of various neurological illnesses. Gene delivery of NTF has the potential to be used as a therapeutic approach for the treatment of neurological problems in the brain. This review primarily focuses on the methodologies employed for delivering the genes of different NTFs to treat neurological disorders. These techniques are currently being explored as a viable therapeutic approach for neurodegenerative diseases. The article exclusively addresses gene delivery approaches and does not cover additional therapy strategies for NDDs. Gene therapy offers a promising alternative treatment for NDDs by stimulating neuronal growth instead of solely relying on symptom relief from drugs and their associated adverse effects. It can serve as a long-lasting and advantageous treatment choice for the management of NDDs. The likelihood of developing NDDs increases with age as a result of neuronal degradation in the brain. Gene therapy is an optimal approach for promoting neuronal growth through the introduction of nerve growth factor genes.

Insights Into Retinal Pathologies in Neurological Disorders: A Focus on Parkinson's Disease, Multiple Sclerosis, Amyotrophic Lateral Sclerosis, and Alzheimer's Disease

Neurological diseases are central nervous system (CNS) disorders affecting the whole body. Early diagnosis of the diseases is difficult due to the lack of disease-specific tests. Adding new biomarkers external to the CNS facilitates the diagnosis of neurological diseases. In this respect, the retina has a common embryologic origin with the CNS. Retinal imaging technologies including optical coherence tomography (OCT) can be used in the understanding and processual monitoring of neurological diseases. Retinal imaging has been recently recognized as a potential source of biomarkers for neurological diseases, increasing the number of studies in this direction. In this review, the association of retinal abnormalities with Parkinson's disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), and Alzheimer's disease (AD) is explained. Structural and functional abnormalities in retina as a predictive marker may facilitate early diagnosis of diseases. Although not all retinal abnormalities are predictive of neurologic diseases, changes in the retinal layers including retinal pigment epithelium and plexiform layers should suggest the risk of PD, MS, ALS, and AD.

Value of MRI-visible perivascular spaces in predicting levodopa responsiveness of patients with Parkinson's disease

PURPOSE

Inter-individual difference in levodopa responsiveness is a challenge for physicians to administer personalized treatment for patients with Parkinson's disease (PD). Previous studies demonstrated that magnetic resonance imaging (MRI)-visible perivascular spaces (PVS) might lead to an incomplete response to levodopa. This study aimed to investigate the association between MRI-visible PVS and levodopa responsiveness in patients with PD.

METHODS

This cross-sectional study enrolled a total of 327 patients with PD (median age 64.0[57.0-68.0] years, 180 male) who had undergone high-resolution T2-weighted structural MRI at our hospital between 2019 and 2023. An acute levodopa challenge test was performed to evaluate levodopa responsiveness. The patients were divided into two groups: levodopa responsive (MDS-UPDRS-III reduction ≥ 33 %, n = 274) and irresponsive groups (MDS-UPDRS-III reduction < 33 %, n = 53). We employed quantitative and semi-quantitative methods to evaluate MRI-visible PVS in patients with PD, including PVS number, volume fraction, and visual score. Additionally, the imaging features of the levodopa-responsive and irresponsive groups were compared.

RESULTS

There were no significant differences in PVS number, volume fraction, and visual score between the levodopa-responsive and -irresponsive groups. The indicators from quantitative and semi-quantitative analyses of PVS were not found to be independent predictors of levodopa responsiveness. None of the indicators from the quantitative or semi-quantitative analyses of PVS were significantly associated with poor responsiveness to levodopa treatment.

CONCLUSIONS

MRI-visible PVS are not independently associated with levodopa responsiveness, and their value in predicting levodopa responsiveness in patients with PD is limited.

Recent progress in the applications of presynaptic dopaminergic positron emission tomography imaging in parkinsonism

Nowadays, presynaptic dopaminergic positron emission tomography, which assesses deficiencies in dopamine synthesis, storage, and transport, is widely utilized for early diagnosis and differential diagnosis of parkinsonism. This review provides a comprehensive summary of the latest developments in the application of presynaptic dopaminergic positron emission tomography imaging in disorders that manifest parkinsonism. We conducted a thorough literature search using reputable databases such as PubMed and Web of Science. Selection criteria involved identifying peer-reviewed articles published within the last 5 years, with emphasis on their relevance to clinical applications. The findings from these studies highlight that presynaptic dopaminergic positron emission tomography has demonstrated potential not only in diagnosing and differentiating various Parkinsonian conditions but also in assessing disease severity and predicting prognosis. Moreover, when employed in conjunction with other imaging modalities and advanced analytical methods, presynaptic dopaminergic positron emission tomography has been validated as a reliable in vivo biomarker. This validation extends to screening and exploring potential neuropathological mechanisms associated with dopaminergic depletion. In summary, the insights gained from interpreting these studies are crucial for enhancing the effectiveness of preclinical investigations and clinical trials, ultimately advancing toward the goals of neuroregeneration in parkinsonian disorders.

Rapamycin Abrogates Aggregation of Human α-Synuclein Expressed in Fission Yeast via an Autophagy-Independent Mechanism

Aggregation of alpha-synuclein (α-Syn) is implicated in the pathogenesis of several neurodegenerative disorders, such as Parkinson's disease and Dementia with Lewy bodies, collectively termed synucleinopathies. Thus, tremendous efforts are being made to develop strategies to prevent or inhibit α-Syn aggregation. Here, we genetically engineered fission yeast to express human α-Syn C-terminally fused to green fluorescent protein (GFP) at low and high levels. α-Syn was localized at the cell tips and septa at low-level expression. At high-level expression, α-Syn was observed to form cytoplasmic aggregates. Notably, rapamycin, a natural product that allosterically inhibits the mammalian target of rapamycin (mTOR) by forming a complex with FKBP12, and Torin1, a synthetic mTOR inhibitor that blocks ATP binding to mTOR, markedly reduced the number of cells harboring α-Syn aggregates. These mTOR inhibitors abrogate α-Syn aggregation without affecting α-Syn expression levels. Rapamycin, but not Torin1, failed to reduce α-Syn aggregation in the deletion cells of fkh1+, encoding FKBP12, indicating the requirement of FKBP12 for rapamycin-mediated inhibition of α-Syn aggregation. Importantly, the effect of rapamycin was also observed in the cells lacking atg1+, a key regulator of autophagy. Collectively, rapamycin abrogates human α-Syn aggregation expressed in fission yeast via an autophagy-independent mechanism mediated by FKBP12.

The co-chaperone DNAJA2 buffers proteasomal degradation of cytosolic proteins with missense mutations

Mutations can disrupt the native function of protein by causing misfolding, which is generally handled by an intricate protein quality control network. To better understand the triaging mechanisms for misfolded cytosolic proteins, we screened a human mutation library to identify a panel of unstable mutations. The degradation of these mutated cytosolic proteins is largely dependent on the ubiquitin proteasome system. Using BioID proximity labelling, we found that the co-chaperones DNAJA1 and DNAJA2 are key interactors with one of the mutated proteins. Notably, the absence of DNAJA2 increases the turnover of the mutant but not the wild-type protein. Our work indicates that specific missense mutations in cytosolic proteins can promote enhanced interactions with molecular chaperones. Assessment of the broader panel of cytosolic mutant proteins shows that the co-chaperone DNAJA2 exhibits two distinct behaviours - acting to stabilize a wide array of cytosolic proteins, including wild-type variants, and to specifically 'buffer' some mutant proteins to reduce their turnover. Our work illustrates how distinct elements of the protein homeostasis network are utilized in the presence of a cytosolic misfolded protein.

Impact of a Dynamic Orthosis on Manual Dexterity Among People With Parkinson's Disease: A Randomized Trial

IMPORTANCE

A dynamic elastomeric fabric orthosis could be a novel nonpharmacological treatment of motor symptoms among people with Parkinson's disease (PD).

OBJECTIVE

To evaluate the efficacy of the orthosis in improving manual dexterity among people with PD.

DESIGN

A randomized trial with 60 participants (control group, n = 20; experimental group, n = 40). Manual dexterity was assessed in on-off states of the disease, with and without the orthosis.

SETTING

Burgos University Hospital (Burgos, Spain).

PARTICIPANTS

Consecutive nonprobabilistic sampling. Patients were included if they had been diagnosed with PD, had motor symptoms in at least one upper limb, and attended the hospital's neurology department. Participants were ages 48 to 89 yr, with an average disease duration of 5.38 yr (SD = 4.23). Exclusion criteria were tremor due to another neurological disease or a Montreal Cognitive Assessment score ≤26.

INTERVENTION

The experimental group used the orthosis on the most affected upper limb for 2 mo; the control group participants did not receive the orthosis.

OUTCOMES AND MEASURES

Manual dexterity was measured with the Purdue Pegboard Test, Minnesota Manual Dexterity Test, and Square Test. Paired t tests for related samples and analysis of covariance tests were used.

RESULTS

Some participants improved on some manual dexterity items while wearing the orthosis. However, it was not sustained when the orthosis was removed after 2 mo of use.

CONCLUSIONS AND RELEVANCE

The orthosis may improve certain aspects of manual dexterity and functionality among people with PD, but only while it is worn. Plain-Language Summary: The common motor symptoms and declines in manual dexterity that people with Parkinson's disease (PD) experience can significantly affect their ability to perform activities of daily living as well as their quality of life. Manual dexterity is a strong predictor of the level of functional independence for people with PD. This study evaluated the efficacy of an elastomeric fabric orthosis to improve manual dexterity for people with PD. The study found that while wearing the orthosis the motor symptoms of PD were reduced and manual dexterity and upper limb functionality improved. Wearing the orthosis has the potential to enhance functionality, foster greater autonomy, and substantially improve the quality of life of people with PD.

Motivators and Barriers Affecting Exercise in Patients With Parkinson's Disease

BACKGROUND AND PURPOSE

Parkinson's disease (PD) significantly impacts the quality of life via both motor and nonmotor symptoms. Exercise is a valuable nonpharmacological intervention that can alleviate PD symptoms and slow disease progression. Understanding the factors that motivate and restrict exercise in PD patients is essential for promoting engagement. This study aimed to identify the motivators and barriers affecting exercise in PD patients.

METHODS

This cross-sectional study assessed exercise habits, motivators, and barriers among PD patients with a modified Hoehn and Yahr stage of ≤2.5. Participants were categorized into non-, low-, and high-exercise groups based on the World Health Organization guidelines. The International Physical Activity Questionnaire, the Korean version of the Sport Motivation Scale, and a barriers-to-exercise questionnaire were utilized.

RESULTS

Data from 165 of 196 enrolled patients were analyzed: 28 (17.0%), 88 (53.3%), and 49 (29.7%) in the non-, low-, and high-exercise groups, respectively. The nonexercise group demonstrated higher levels of fatigue and apathy, and more-severe cardiovascular, mood, intellectual, attention, gastrointestinal, and urinary symptoms. While all groups recognized the benefit of exercise, those in the nonexercise group viewed PD symptoms and depressive mood as major barriers, whereas those in the high-exercise group were primarily motivated by personal satisfaction.

CONCLUSIONS

This study highlights the importance of enjoyment and personal satisfaction to the maintenance of exercise habits among PD patients. By enhancing specific motivators and overcoming barriers, particularly PD symptoms and related nonmotor symptoms, tailored interventions can be implemented to increase exercise adherence and, eventually, improve the quality of life of PD patients.

Dopaminergic Axon Tracts Within a Hyaluronic Acid Hydrogel Encasement to Restore the Nigrostriatal Pathway

Parkinson's disease is characterized by motor deficits emerging from insufficient dopamine in the striatum after degeneration of dopaminergic neurons and their long-projecting axons comprising the nigrostriatal pathway. To address this, a tissue-engineered nigrostriatal pathway (TE-NSP) featuring a tubular hydrogel with a collagen/laminin core that encases aggregated dopaminergic neurons and their axonal tracts is developed. This engineered microtissue can be implanted to replace neurons and axons with fidelity to the lost pathway and thus may provide dopamine according to feedback from host circuitry. While TE-NSPs have traditionally been fabricated with agarose, here a hyaluronic acid (HA) hydrogel is utilized to have a more bioactive encasement while expanding control over physical and biochemical properties. Using rat ventral midbrain neurons, it is found that TE-NSPs exhibited improved neurite growth with HA relative to agarose, with no differences in electrically-evoked dopamine release. When transplanted, HA hydrogels reduced average host neuron loss and inflammation around the implant compared to agarose, and TE-NSP neurons and axonal tracts survived for at least 2 weeks to structurally emulate the lost pathway. This study represents an innovative use of HA hydrogels for neuroregenerative medicine and enables future studies expanding the control and functionality of TE-NSPs.

Calcium Signalling in Neurological Disorders, with Insights from Miniature Fluorescence Microscopy

Neurological disorders (NDs), such as amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and schizophrenia, represent a complex and multifaceted health challenge that affects millions of people around the world. Growing evidence suggests that disrupted neuronal calcium signalling contributes to the pathophysiology of NDs. Additionally, calcium functions as a ubiquitous second messenger involved in diverse cellular processes, from synaptic activity to intercellular communication, making it a potential therapeutic target. Recently, the development of the miniature fluorescence microscope (miniscope) enabled simultaneous recording of the spatiotemporal calcium activity from large neuronal ensembles in unrestrained animals, providing a novel method for studying NDs. In this review, we discuss the abnormalities observed in calcium signalling and its potential as a therapeutic target for NDs. Additionally, we highlight recent studies that utilise miniscope technology to investigate the alterations in calcium dynamics associated with NDs.

Autophagic signatures in peripheral blood mononuclear cells from Parkinson's disease patients

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by motor impairments and the accumulation of misfolded α-synuclein. Dysregulation of the autophagy-lysosomal pathway (ALP), responsible for degrading misfolded proteins, has been implicated in PD pathogenesis. However, current diagnostic approaches rely heavily on motor symptoms, which occur due to substantial neurodegeneration, limiting early detection and intervention. This study investigated the potential of ALP-associated proteins in peripheral blood mononuclear cells (PBMCs) as diagnostic biomarkers for early-stage PD. Quantitative analysis revealed a significant reduction in optineurin levels in PBMCs from PD patients, and the expression levels of various ALP-associated proteins were tightly correlated, suggesting a coordinated dysregulation of the pathway. Correlation analyses revealed associations between ALP-associated features and clinical characteristics, such as age of onset and motor impairment. Furthermore, the study identified multiple positive correlations among ALP-associated proteins and functional readouts, highlighting the interconnectivity within the pathway. Notably, a PBMC biomarker model incorporating lysosomal-associated membrane protein 1 and optineurin exhibited high diagnostic accuracy (86%) in distinguishing PD patients from controls. These findings highlight the potential of ALP-associated protein signatures in PBMCs as novel diagnostic biomarkers for early detection and intervention in PD, offering insights into the systemic manifestations of the disease.

Endosomal traffic disorders: a driving force behind neurodegenerative diseases

Endosomes are crucial sites for intracellular material sorting and transportation. Endosomal transport is a critical process involved in the selective uptake, processing, and intracellular transport of substances. The equilibrium between endocytosis and circulation mediated by the endosome-centered transport pathway plays a significant role in cell homeostasis, signal transduction, and immune response. In recent years, there have been hints linking endosomal transport abnormalities to neurodegenerative diseases, including Alzheimer's disease. Nonetheless, the related mechanisms remain unclear. Here, we provide an overview of endosomal-centered transport pathways and highlight potential physiological processes regulated by these pathways, with a particular focus on the correlation of endosomal trafficking disorders with common pathological features of neurodegenerative diseases. Additionally, we summarize potential therapeutic agents targeting endosomal trafficking for the treatment of neurodegenerative diseases.

Base editing of Ptbp1 in neurons alleviates symptoms in a mouse model of Parkinson's disease

Parkinson's disease (PD) is a multifactorial disease caused by irreversible progressive loss of dopaminergic neurons (DANs). Recent studies have reported the successful conversion of astrocytes into DANs by repressing polypyrimidine tract binding protein 1 (PTBP1), which led to the rescue of motor symptoms in a chemically-induced mouse model of PD. However, follow-up studies have questioned the validity of this astrocyte-to-DAN conversion model. Here, we devised an adenine base editing strategy to downregulate PTBP1 in astrocytes and neurons in a chemically-induced PD mouse model. While PTBP1 downregulation in astrocytes had no effect, PTBP1 downregulation in neurons of the striatum resulted in the expression of the DAN marker tyrosine hydroxylase (TH) in non-dividing neurons, which was associated with an increase in striatal dopamine concentrations and a rescue of forelimb akinesia and spontaneous rotations. Phenotypic analysis using multiplexed iterative immunofluorescence imaging further revealed that most of these TH-positive cells co-expressed the dopaminergic marker DAT and the pan-neuronal marker NEUN, with the majority of these triple-positive cells being classified as mature GABAergic neurons. Additional research is needed to fully elucidate the molecular mechanisms underlying the expression of the observed markers and understand how the formation of these cells contributes to the rescue of spontaneous motor behaviors. Nevertheless, our findings support a model where downregulation of neuronal, but not astrocytic, PTBP1 can mitigate symptoms in PD mice.

Multi-label speech feature selection for Parkinson's Disease subtype recognition using graph model

Parkinson's Disease (PD) is the second-most common neurodegenerative disorder. There is a certain pathological connection between PD and dysphonia. Speech signals have been successfully used to identify PD and predict its severity. Moreover, PD has several subtypes, such as tremor, freezing of gait and dysphagia. The recognition of subtypes is of great significance for the diagnosis and treatment of PD. In this paper, we consider PD subtype recognition as a multi-label learning task and try to simultaneously recognize these subtypes using speech signals. In the proposed recognition framework, multiple types of speech data are collected, such as/a/,/pa-ka-la/, etc., and different speech features are extracted from different types of speech data. The features are concatenated as the representation of speech data. Especially, a multi-label speech feature selection algorithm based on graph structure is proposed to choose the key features and followed by a multi-label classifier for PD subtype recognition. The speech samples of 70 PD patients are collected as speech corpus. Experimental results show that the proposed multi-label feature selection method can obtain higher recognition performance than other classical ones in most cases.

Brazilin-Rich Extract from Caesalpinia sappan L. Attenuated the Motor Deficits and Neurodegeneration in MPTP/p-Induced Parkinson's Disease Mice by Regulating Gut Microbiota and Inhibiting Inflammatory Responses

Parkinson's disease (PD) is a complicated neurological disease with an unclear pathogenesis. However, dysregulation of gut microbiota and inflammation response play crucial roles in the progression of PD. Caesalpinia sappan L., a traditional medicinal plant containing brazilin as its primary active compound, is known for its anti-inflammatory and neuroprotective properties. However, the impact of C. sappan L. extract (SE) on PD through the regulation of the microbiota-gut-brain axis remains unclear. This study investigated the effects and mechanisms of a 91.23% brazilin-enriched SE on MPTP/p-induced PD mice. Results showed that SE significantly ameliorated motor deficits and protected dopaminergic neurons in PD mice. Additionally, SE reduced oxidative stress and inflammation in the brain. SE also restored gut microbiota by increasing Firmicutes and decreasing Bacteroidetes, alongside enhancing the production of short-chain fatty acids (SCFAs) like butyric acid. Furthermore, SE mitigated intestinal barrier damage by enhancing the expression of ZO-1 and occludin, thereby decreasing lipopolysaccharide leakage and inflammatory factor release. Molecular simulations suggested that butyric acid may maintain intestinal integrity by stabilizing ZO-I and occludin conformations. In conclusion, SE exhibited a protective effect on motor deficits and neurodegeneration in PD by regulating gut microbiota and SCFAs, repairing the intestinal barrier, and mitigating inflammatory responses.

Early alterations of functional connectivity, regional brain volumes and astrocyte markers in the beta-sitosterol beta-d-glucoside (BSSG) rat model of parkinsonism

The β-sitosterol-β-ᴅ-glucoside (BSSG) rat model of experimental parkinsonism develops pathological behaviour and motor changes that progress over time. The purpose of this study was to identify early changes in structure and function of the brain of rats treated with BSSG using both structural and resting-state functional MRI. BSSG and non-BSSG rats were fed five days a week for sixteen weeks, then underwent in vivo MRI scans and an assessment of motor performance 2 and 8 weeks later (18 and week 24 from BSSG). Groups of rats were killed at weeks 19 and 25, then imaged again with MR ex vivo, and immunostained for tyrosine hydroxylase (TH). Since BSSG may interfere with cholesterol metabolism in astrocytes, we also studied potential target engagement and measured levels of astrocyte markers GFAP and S100b. At both studied timepoints, functional connectivity (FC) between brain areas with intermediate connectivity was decreased, but brain volumes increased in the BSSG-treated rats. At week 18/19, fine movements were normal, whereas TH and GFAP were decreased in the striatum, but not in the substantia nigra. At week 24/25, fine movements were impaired, and TH was decreased both in the striatum and the substantia nigra and S100b was increased in the substantia nigra. Astrogliosis may contribute to the increased brain volume found after BSSG exposure. Using the BSSG model of parkinsonism, the results demonstrate early functional and structural alterations in MRI imaging that occur before the appearance of detectable motor symptoms.

BCKDK loss impairs mitochondrial Complex I activity and drives alpha-synuclein aggregation in models of Parkinson's disease

Mitochondrial dysfunction and α-synuclein (αSyn) aggregation are key contributors to Parkinson's Disease (PD). While genetic and environmental risk factors, including mutations in mitochondrial-associated genes, are implicated in PD, the precise mechanisms linking mitochondrial defects to αSyn pathology remain incompletely understood, hindering the development of effective therapeutic interventions. Here, we identify the loss of branched chain ketoacid dehydrogenase kinase (BCKDK) as a mitochondrial risk factor that exacerbates αSyn pathology by disrupting Complex I function. Our findings reveal a consistent downregulation of BCKDK in dopaminergic (DA) neurons from A53T-αSyn mouse models, PD patient-derived induced pluripotent stem (iPS) cells, and postmortem brain tissues. BCKDK deficiency leads to mitochondrial dysfunction, including reduced membrane potential and increased reactive oxygen species (ROS) production upon administration of a stressor, which in turn promotes αSyn oligomerization. Mechanistically, BCKDK interacts with the NDUFS1 subunit of Complex I to stabilize its function. Loss of BCKDK disrupts this interaction, leading to Complex I destabilization and enhanced αSyn aggregation. Notably, restoring BCKDK expression in neuron-like cells rescues mitochondrial integrity and restores Complex I activity. Similarly, in patient-derived iPS cells differentiated to form dopaminergic neurons, NDUFS1 and phosphorylated aSyn levels are partially restored upon BCKDK expression. These findings establish a mechanistic link between BCKDK deficiency, mitochondrial dysfunction, and αSyn pathology in PD, positioning BCKDK as a potential therapeutic target to mitigate mitochondrial impairment and neurodegeneration in PD.

Paracentrotus lividus sea urchin gonadal extract mitigates neurotoxicity and inflammatory signaling in a rat model of Parkinson's disease

The present study investigates the neuroprotective effects of the sea urchin Paracentrotus lividus gonadal extract on rotenone-induced neurotoxicity in a Parkinson's disease (PD) rat model. Parkinson's disease, characterized by the progressive loss of dopaminergic neurons in the substantia nigra (SN), is exacerbated by oxidative stress and neuroinflammation. The study involved fifty Wistar rats divided into five groups: control, dimethyl sulfoxide (DMSO) control, Paracentrotus lividus gonadal extract-treated, rotenone-treated, and combined rotenone with Paracentrotus lividus gonadal extract-treated. Behavioral assessments included the rotarod and open field tests, while biochemical analyses measured oxidative stress markers (malondialdehyde (MDA), nitric oxide (NO), glutathione (GSH)), antioxidants (superoxide dismutase (SOD), catalase (CAT)), pro-inflammatory cytokines (interleukin-1 beta (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α)), and neurotransmitters (dopamine (DA), levodopa (L-Dopa)). Histological and immunohistochemical analyses evaluated the neuronal integrity and tyrosine hydroxylase (TH) and alpha-synuclein expression. The results showed that Paracentrotus lividus gonadal extract significantly mitigated rotenone-induced motor deficits and improved locomotor activity. Biochemically, the extract reduced oxidative stress and inflammation markers while enhancing antioxidant levels. Histologically, it restored neuronal integrity and reduced alpha-synuclein accumulation. Molecularly, it increased tyrosine hydroxylase and dopa decarboxylase gene expression, essential for dopamine synthesis. These findings suggest that Paracentrotus lividus gonadal extract exerts neuroprotective effects by modulating oxidative stress, neuroinflammation, and dopaminergic neuron integrity, highlighting its potential as a therapeutic agent for Parkinson's disease.

Inhibition of neuroinflammation by GIBH-130 (AD-16) reduces neurodegeneration, motor deficits, and proinflammatory cytokines in a hemiparkinsonian model

Parkinson's disease (PD) is a neurodegenerative condition characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta (SNc) of the brain, manifesting itself with both motor and non-motor symptoms. A critical element of this pathology is neuroinflammation, which triggers a harmful neurotoxic cycle, exacerbating cell death within the central nervous system. AD-16 (also known as GIBH-130) is a recently identified compound capable of reducing the expression of pro-inflammatory cytokines while increasing the expression of anti-inflammatory cytokines in Alzheimer's disease models. Here, for the first time, we sought to comprehend the potential impact of orally administered AD-16 in mitigating neurodegeneration and subsequent disease progression in PD. To accomplish this, 6- hydroxydopamine (6-OHDA) unilateral striatal injections were employed to induce a PD model in male C57BL/6 mice. Cylinder and apomorphine-induced rotation behavior tests were conducted to assess motor behavior and validate the PD model 3 days after the injection. AD-16 was administered via gavage daily between days 3 and 9 after surgery. On the last day of treatment, motor tests were performed again. All animals were euthanized on day 10 and immunohistochemistry techniques were performed to detect tyrosine hydroxylase (TH) and Iba-1 and thus label dopaminergic neurons and microglia in the SNc and striatum (CPu). These same regions were collected for ELISA assays to assess different cytokine concentrations. Our results revealed an enhancement in the motor function of the AD-16-treated animals, as well as reduced nigrostriatal neurodegeneration. In addition, AD-16 reduced the increase in microglia density and prevented the changes in its morphology observed in the PD animal models. Furthermore, AD-16 was able to avoid the increase of pro-inflammatory cytokines levels that were present in 6-OHDA-injected animals who received vehicle. Consequently, AD-16 emerges as a compound with significant potential for negative modulation of neurodegeneration and neuroinflammation suppression in the 6-OHDA animal model of Parkinson's disease.

The crucial role of VPS35 and SHH in Parkinson's disease: Understanding the mechanisms behind the neurodegenerative disorder

Parkinson's disease (PD) is indeed a complex neurodegenerative disorder recognized by the progressive depletion of dopaminergic neurons in the brain, particularly in the substantia nigra region, leading to motor impairments and other symptoms. But at the molecular level, the study about PD still lacks. As the number of cases worldwide continues to increase, it is critical to focus on the cellular and molecular mechanisms of the disease's presentation and neurodegeneration to develop novel therapeutic approaches. At the molecular level, the complexity is more due to the involvement of vacuolar protein sorting 35 (VPS35) and sonic hedgehog (SHH) signaling in PD (directly or indirectly), leading to one of the most prominent hallmarks of the disease, which is an accumulation of α-synuclein. This elevated pathogenesis may result from impaired autophagy due to mutation in the case of VPS35 and impairment in SHH signaling at the molecular level. The traditional understanding of PD is marked by the disruption of dopaminergic neurons and dopaminergic signaling, which exacerbates symptoms of motor function deficits. However, the changes at the molecular level that are being disregarded also impact the overall health of the dopaminergic system. Gaining insight into these two unique mechanisms is essential to determine whether they give neuroprotection or have no effect on the health of neurons. Hence, here we tried to simplify the understanding of the role of VPS35 and SHH signaling to comprehend it in one direction.

Hyperglycemia-Driven Insulin Signaling Defects Promote Parkinson's Disease-like Pathology in Mice

This study aims to determine the effect of chronic hyperglycemia, induced by a high-fat diet and STZ-induced diabetes, on the development of Parkinson's disease-like characteristics. Understanding this relationship is crucial in pharmacology, neurology, and diabetes, as it could potentially lead to developing new therapeutic strategies for Parkinson's disease. Our study employed a comprehensive approach to investigate the effect of hyperglycemia on Parkinson's disease-like characteristics. Hyperglycemia was induced by a high-fat diet for 6- and 9-week duration with a single intraperitoneal STZ (100 mg/kg) injection at week 5 in C57/BL6 mice. Rotenone (10 mg/kg p.o.) was administered to C57/BL6 mice for 6 and 9 weeks. Time-dependent behavioral studies (wire-hang tests, pole tests, Y-maze tests, and round beam walk tests) were carried out to monitor pathology progression and deficits. Molecular protein levels (GLP1, PI3K, AKT, GSK-3β, NF-κB, and α-syn), oxidative stress (GSH and MDA) parameters, and histopathological alterations (H&E and Nissl staining) were determined after 6 weeks as well as 9 weeks. After 9 weeks of study, molecular protein expression (p-AKT and p-α-syn) was determined. Hyperglycemia induced by HFD and STZ induced significant motor impairment in mice, correlated with the rotenone group. Insulin receptor signaling (GLP1/PI3K/AKT) was found to be disrupted in the HFD+STZ group and also in rotenone-treated mice, which further enhanced phosphorylation of α-syn, suggesting its role in α-syn accumulation. Histopathological alterations indicating neuroinflammation and neurodegeneration were quite evident in the HFD+STZ and rotenone groups. Exposure to hyperglycemia induced by HFD+STZ administration exhibits PD-like characteristics after 9 weeks of duration, which was correlative with rotenone-induced PD-like symptoms.

Effectiveness of robot-assisted training in adults with Parkinson's disease: a systematic review and meta-analysis

AIM

This work aimed to update and summarize the existing evidence on the effectiveness of robot-assisted training (RAT) in adults with Parkinson's disease (PD).

METHODS

We conducted a systematic review with meta-analysis, reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines (PROSPERO CRD42022371124). Seven databases and two trial registries were searched for randomized-controlled trials (RCTs) addressing RAT alone or in addition to other treatments in adults with PD up to January 2024. Primary outcomes were disease-specific motor impairment, balance, mobility, freezing of gait, falls, number of people who fell at least once, and adverse events. Meta-analysis using a random-effects model was performed. Risk of bias (RoB) and certainty of the evidence for the primary outcomes were assessed using the Cochrane RoB Tool and the Grades of Recommendation Assessment, Development, and Evaluation (GRADE) approach, respectively.

RESULTS

Fifteen RCTs (629 randomized adults with PD) were included. Our results show that the evidence is very uncertain about the effectiveness of any kind of RAT, either focused on gait, balance or upper limb impairment, compared to any comparator (treadmill training, overground gait training, exercises without the exoskeleton, conventional physical therapy, balance training, and no treatment), mainly because of RoB, inconsistency in individual studies results, and very limited number (less than 200) of participants considered in each comparison.

CONCLUSION

In light of the aforementioned very low certainty evidence, clinical considerations should be drawn very carefully. High-quality studies are thus highly needed to investigate potential benefits, risks, and cost/benefit ratio of RAT in adults with PD.

LRRK2 mutation contributes to decreased free water in the nucleus basalis of Meynert in manifest and premanifest Parkinson's disease

BACKGROUND

Free-water imaging can predict and monitor dopamine system degeneration in patients with Parkinson's disease (PD). However, brain cholinergic function has not been investigated to date in LRRK2 mutation carriers with or without PD using free-water imaging.

OBJECTIVES

To investigate the effect of LRRK2 mutations on the cholinergic system in manifest and premanifest stages of PD using free-water imaging.

METHODS

We recruited participants from the Parkinson's Progression Markers Initiative (PPMI) data set. We evaluated the effect of LRRK2 mutations on the cholinergic nuclei (i.e., cholinergic nuclei 1, 2, and 3 (Ch123), Ch4, and pedunculopontine nucleus) in manifest and premanifest stages of PD using free-water imaging. We compared free-water values between groups using ANCOVA with adjustment for age. Then, the discriminative power of the free-water content was evaluated by receiver operating characteristic curve (ROC) analysis.

RESULTS

We included 27 patients with LRRK2 PD, 33 LRRK2 mutation carriers without PD, 281 patients with idiopathic PD, and 98 healthy controls. We noted significant between-group differences in free-water content in Ch4 (p = 0.003). LRRK2 mutation carriers without PD had decreased free-water content in the Ch4 compared with healthy controls (p = 0.036) and idiopathic patients with PD (p = 0.001); LRRK2 patients with PD showed decreased tendency of free-water content in the Ch4 compared with idiopathic patients with PD (p = 0.074). Furthermore, ROC analysis showed that free-water content in the Ch4 identified asymptomatic LRRK2 mutation carriers with a high specificity (84.7%).

CONCLUSIONS

LRRK2 mutation is associated with decreased free-water content in the Ch4 (also referred to as nucleus basalis of Meynert, nbM), which might suggest early and sustained attempts to compensate for LRRK2-related dysfunction.

Intermittent fasting and neurodegenerative diseases: Molecular mechanisms and therapeutic potential

Neurodegenerative disorders are straining public health worldwide. During neurodegenerative disease progression, aberrant neuronal network activity, bioenergetic impairment, adaptive neural plasticity impairment, dysregulation of neuronal Ca2+ homeostasis, oxidative stress, and immune inflammation manifest as characteristic pathological changes in the cellular milieu of the brain. There is no drug for the treatment of neurodegenerative disorders, and therefore, strategies/treatments for the prevention or treatment of neurodegenerative disorders are urgently needed. Intermittent fasting (IF) is characterized as an eating pattern that alternates between periods of fasting and eating, requiring fasting durations that vary depending on the specific protocol implemented. During IF, depletion of liver glycogen stores leads to the production of ketone bodies from fatty acids derived from adipocytes, thereby inducing an altered metabolic state accompanied by cellular and molecular adaptive responses within neural networks in the brain. At the cellular level, adaptive responses can promote the generation of synapses and neurons. At the molecular level, IF triggers the activation of associated transcription factors, thereby eliciting the expression of protective proteins. Consequently, this regulatory process governs central and peripheral metabolism, oxidative stress, inflammation, mitochondrial function, autophagy, and the gut microbiota, all of which contribute to the amelioration of neurodegenerative disorders. Emerging evidence suggests that weight regulation significantly contributes to the neuroprotective effects of IF. By alleviating obesity-related factors such as blood-brain barrier dysfunction, neuroinflammation, and β-amyloid accumulation, IF enhances metabolic flexibility and insulin sensitivity, further supporting its potential in mitigating neurodegenerative disorders. The present review summarizes animal and human studies investigating the role and underlying mechanisms of IF in physiology and pathology, with an emphasis on its therapeutic potential. Furthermore, we provide an overview of the cellular and molecular mechanisms involved in regulating brain energy metabolism through IF, highlighting its potential applications in neurodegenerative disorders. Ultimately, our findings offer novel insights into the preventive and therapeutic applications of IF for neurodegenerative disorders.

Neuroprotective effects of GLP-1 class drugs in Parkinson's disease

Parkinson's disease (PD) is a chronic, progressive neurological disorder primarily affecting motor control, clinically characterized by resting tremor, bradykinesia, rigidity, and other symptoms that significantly diminish the quality of life. Currently, available treatments only alleviate symptoms without halting or delaying disease progression. There is a significant association between PD and type 2 diabetes mellitus (T2DM), possibly due to shared pathological mechanisms such as insulin resistance, chronic inflammation, and mitochondrial dysfunction. PD is caused by a deficiency of dopamine, a neurotransmitter in the brain that plays a critical role in the control of movement. Glucose metabolism and energy metabolism disorders also play an important role in the pathogenesis of PD. This review investigates the neuroprotective mechanisms of glucagon-like peptide-1 (GLP-1) and its receptor agonists, offering novel insights into potential therapeutic strategies for PD. GLP-1 class drugs, primarily used in diabetes management, show promise in addressing PD's underlying pathophysiological mechanisms, including energy metabolism and neuroprotection. These drugs can cross the blood-brain barrier, improve insulin resistance, stabilize mitochondrial function, and enhance neuronal survival and function. Additionally, they exhibit significant anti-inflammatory and antioxidative stress effects, which are crucial in neurodegenerative diseases like PD. Research indicates that GLP-1 receptor agonists could improve both motor and cognitive symptoms in PD patients, marking a potential breakthrough in PD treatment and prevention. Further exploration of GLP-1's molecular mechanisms in PD could provide new preventive and therapeutic approaches, especially for PD patients with concurrent T2DM. By targeting both metabolic and neurodegenerative pathways, GLP-1 receptor agonists represent a multifaceted approach to PD treatment, offering hope for better disease management and improved patient outcomes.

From onset to advancement: the temporal spectrum of α-synuclein in synucleinopathies

This review provides an in-depth analysis of the complex role of alpha-synuclein (α-Syn) in the development of α-synucleinopathies, with a particular focus on its structural diversity and the resulting clinical variability. The ability of α-Syn to form different strains or polymorphs and undergo various post-translational modifications significantly contributes to the wide range of symptoms observed in disorders such as Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA), as well as in lesser-known non-classical α-synucleinopathies. The interaction between genetic predispositions and environmental factors further complicates α-synucleinopathic disease pathogenesis, influencing the disease-specific onset and progression. Despite their common pathological hallmark of α-Syn accumulation, the clinical presentation and progression of α-synucleinopathies differ significantly, posing challenges for diagnosis and treatment. The intricacies of α-Syn pathology highlight the critical need for a deeper understanding of its biological functions and interactions within the neuronal environment to develop targeted therapeutic strategies. The precise point at which α-Syn aggregation transitions from being a byproduct of initial disease triggers to an active and independent driver of disease progression - through the propagation and acceleration of pathogenic processes - remains unclear. By examining the role of α-Syn across various contexts, we illuminate its dual role as both a marker and a mediator of disease, offering insights that could lead to innovative approaches for managing α-synucleinopathies.