Understanding Dopaminergic Cell Death Pathways in Parkinson Disease

Hidden face of Parkinson's disease: Is it a new autoimmune disease?

Parkinson's disease is a neurodegenerative disorder marked by the degeneration of dopaminergic neurons and clinical symptoms such as tremors, rigidity, and slowed movements. A key feature of Parkinson's disease is the accumulation of misfolded α-synuclein, forming insoluble Lewy bodies in the substantia nigra pars compacta, which contributes to neurodegeneration. These α-synuclein aggregates may act as autoantigens, leading to T-cell-mediated neuroinflammation and contributing to dopaminergic cell death. Our perspective explores the hypothesis that Parkinson's disease may have an autoimmune component, highlighting research that connects peripheral immune responses with neurodegeneration. T cells derived from Parkinson's disease patients appear to have the potential to initiate an autoimmune response against α-synuclein and its modified peptides, possibly leading to the formation of neo-epitopes. Recent evidence associates Parkinson's disease with abnormal immune responses, as indicated by increased levels of immune cells, such as CD4 + and CD8 + T cells, observed in both patients and mouse models. The convergence of T cells filtration increasing major histocompatibility complex molecules, and the susceptibility of dopaminergic neurons supports the hypothesis that Parkinson's disease may exhibit autoimmune characteristics. Understanding the immune mechanisms involved in Parkinson's disease will be crucial for developing therapeutic strategies that target the autoimmune aspects of the disease. Novel approaches, including precision medicine based on major histocompatibility complex/human leukocyte antigen typing and early biomarker identification, could pave the way for immune-based treatments aimed at slowing or halting disease progression. This perspective explores the relationship between autoimmunity and Parkinson's disease, suggesting that further research could deepen understanding and offer new therapeutic avenues. In this paper, it is organized to provide a comprehensive perspective on the autoimmune aspects of Parkinson's disease. It investigates critical areas such as the autoimmune response observed in Parkinson's disease patients and the role of autoimmune mechanisms targeting α-synuclein in Parkinson's disease. The paper also examines the impact of CD4 + T cells, specifically Th1 and Th17, on neurons through in vitro and ex vivo studies. Additionally, it explores how α-synuclein influences glia-induced neuroinflammation in Parkinson's disease. The discussion extends to the clinical implications and therapeutic landscape, offering insights into potential treatments. Consequently, we aim to provide a comprehensive perspective on the autoimmune aspects of Parkinson's disease, incorporating both supportive and opposing views on its classification as an autoimmune disorder and exploring implications for clinical applications.

Alpha-synuclein mutations mislocalize cytoplasmic p300 compromising autophagy, which is rescued by ACLY inhibition

Triplications and certain point mutations in the SNCA gene, encoding alpha-synuclein (α-Syn), cause Parkinson's disease (PD). Here, we demonstrate that the PD-causing A53T α-Syn mutation and elevated α-Syn expression perturb acetyl-coenzyme A (CoA) and p300 biology in human neurons and in the CNS of zebrafish and mice. This dysregulation is mediated by activation of ATP-citrate lyase (ACLY), a key enzyme that generates acetyl-CoA in the cytoplasm, via two mechanisms. First, ACLY activity increases acetyl-CoA levels, which activate p300. Second, ACLY activation increases LKB1 acetylation, which inhibits AMPK, leading to increased cytoplasmic and decreased nuclear p300. This lowers histone acetylation and increases acetylation of cytoplasmic p300 substrates, like raptor, which causes mechanistic target of rapamycin complex 1 (mTORC1) hyperactivation, thereby impairing autophagy. ACLY inhibitors rescue pathological phenotypes in PD neurons, organoids, zebrafish, and mouse models, suggesting that this pathway is a core feature of α-Syn toxicity and that ACLY may be a suitable therapeutic target.

Iron metabolism and ferroptosis in health and diseases: The crucial role of mitochondria in metabolically active tissues

Iron is essential in various physiological processes, but its accumulation leads to oxidative stress and cell damage, thus iron homeostasis has to be tightly regulated. Ferroptosis is an iron-dependent non-apoptotic regulated cell death characterized by iron overload and reactive oxygen species accumulation. Mitochondria are organelles playing a crucial role in iron metabolism and involved in ferroptosis. MitoNEET, a protein of mitochondrial outer membrane, is a key element in this process. Ferroptosis, altering iron levels in several metabolically active organs, is linked to several non-communicable diseases. For example, iron overload in the liver leads to hepatic fibrosis and cirrhosis, accelerating non-alcholic fatty liver diseases progression, in the muscle cells contributes to oxidative damage leading to sarcopenia, and in the brain is associated to neurodegeneration. The aim of this review is to investigate the intricate balance of iron regulation focusing on the role of mitochondria and oxidative stress, and analyzing the ferroptosis implications in health and disease.

Caloric Restriction Mimetics as Priming Agents of Mesenchymal Stem Cells Secretome to Enhance Regenerative Responses to Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative disorder primarily defined by the deterioration of motor function and characterized by the loss of dopaminergic neurons in the nigrostriatal system. Although it is the second most prevalent disorder of the central nervous system, current treatments primarily focus on symptom management and modestly slowing disease progression, ultimately failing to preserve the long-term quality of life of a substantial proportion of affected individuals. Innovative therapies that can restore neuronal function have emerged, such as the use of the secretome of Mesenchymal Stem Cells (MSCs) due to their rich composition of bioactive molecules. This therapy exhibits robust paracrine activity that drives most of the self-renewal capacity, differentiation potential, and immune regulation of MSCs without presenting compatibility issues often associated with stem cell-based therapies. While conceptually appealing, the clinical application of this approach is still limited by the availability and proliferation capacity of MSCs, as it impacts not only secretome production but also its quality. Various protocols have been developed to enhance secretome action by adding various compounds to cell culture media, given the high environmental plasticity of MSCs. Some of the compounds already used are Caloric Restriction Mimetics (CRMs), molecules that mimic Caloric Restriction (CR) conditions, which have been demonstrated to extend lifespan and reduce age-related diseases in various organisms. While not sufficient to cure neurodegenerative disorders, these compounds may potentiate secretome efficiency by enhancing autophagy pathways and relieving oxidative stress burden from MSCs. Therefore, in this article, we aim to explore the effects of CRMs priming on MSCs and how it may help bridge existing gaps in regenerative therapies for PD.

Olfactory Dysfunction in a Novel Model of Prodromal Parkinson's Disease in Adult Zebrafish

Olfactory dysfunction is a clinical marker of prodromal Parkinson's disease (PD), yet the underlying mechanisms remain unclear. To explore this relationship, we developed a zebrafish model that recapitulates the olfactory impairment observed in prodromal PD without affecting motor function. We used zebrafish due to their olfactory system's similarity to mammals and their unique nervous system regenerative capacity. By injecting 6-hydroxydopamine (6-OHDA) into the dorsal telencephalic ventricle, we observed a significant loss of dopaminergic (DA) periglomerular neurons in the olfactory bulb (OB) and retrograde degeneration of olfactory sensory neurons (OSNs) in the olfactory epithelium (OE). These alterations impaired olfactory responses to cadaverine, an aversive odorant, while responses to alanine remained intact. 6-OHDA also triggered robust neuroinflammatory responses. By 7 days post-injection, dopaminergic synapses in the OB were remodeled, OSNs in the OE appeared recovered, and neuroinflammation subsided, leading to full recovery of olfactory responses to cadaverine. These findings highlight the remarkable neuroplasticity of zebrafish and suggest that this model of olfactory dysfunction associated with dopaminergic loss could provide valuable insights into some features of early PD pathology. Understanding the interplay between dopaminergic loss and olfactory dysfunction in a highly regenerative vertebrate may inform therapeutic strategies for individuals suffering from olfactory loss.

PI3K/mTOR Signaling Pathway Dual Inhibition for the Management of Neuroinflammation: Novel Insights from In Vitro Models

Neuroinflammatory responses are central to the pathogenesis of neurodegenerative diseases, affecting cells of both neuronal and glial origin that respond to immune-driven inflammatory stimuli. The PI3K/mTOR signaling pathway is essential for the regulation of these neuroinflammatory processes and is therefore a promising target for therapeutic intervention. Here, we investigated the consequences of PI3K/mTOR pathway inhibition on neuroinflammation employing PF-04691502, an agent with combined PI3K and mTOR inhibitory activity. We treated SH-SY5Y, C6, BV-2, and Mo3.13 cell lines with PF-04691502 at concentrations of 0.1, 0.5, and 1 µM to assess the modulation of neuroinflammatory responses. To induce inflammation, cells were stimulated with lipopolysaccharide (LPS, 1 μg/mL) and interferon-gamma (IFN-γ, 100 U/mL). The results from the MTT assays demonstrated that PI3K/mTOR inhibition preserved cell viability at 0.5 and 1 µM across all of the cell lines, indicating its potential to mitigate inflammation-driven cytotoxicity. Subsequent ELISA assays revealed a marked decrease in the NF-κB and pro-inflammatory cytokine levels, confirming the effective suppression of inflammation through PI3K/mTOR inhibition. In addition, the SH-SY5Y cell line was exposed to MPP+ to simulate Parkinson's disease (PD)-like toxicity; then, cell viability, PD-associated markers, and apoptotic indicators were assessed. Our results indicate that inhibition of the PI3K/mTOR signaling axis may alleviate neurodegenerative processes by modulating both neuroinflammatory responses and apoptotic pathways. These findings highlight the therapeutic promise of targeting PI3K/mTOR in the context of neurodegenerative disorders and support the need for further validation through in vivo and clinical investigations.

α-Synuclein targeted therapy with multiple pathological improvement for Parkinson's disease by macrocyclic amphiphile nanomedicine

The toxic species formed by the pathological aggregation of α-synuclein (α-Syn) is one of the core pathogenic mechanisms in Parkinson's disease, leading to mitochondrial dysfunction, oxidative stress and ultimately degeneration and loss of dopaminergic neurons. Developing effective inhibitors targeting α-Syn fibrillization critically requires the simultaneous achievement of (1) strong and selective binding of α-Syn for efficient disintegration of fibrils, as well as (2) robust transmembrane capability for efficient cellular uptake. Herein, the co-assembly of guanidinium-modified calixarene (GCA) and cyclodextrin (CD), termed GCA-CD, is screened fully accommodating these conditions. GCA-CD binds tightly and selectively towards α-Syn, thereby effectively inhibiting α-Syn aggregation and disintegrating its fibrils, meanwhile the guanidinium of GCA can additionally improve the transmembrane capability of the co-assembly. In vivo investigations demonstrate that the GCA-CD nanomedicine significantly rescues motor deficits and nigrostriatal degeneration of PD-like rats by decreasing the content of α-Syn as well as restoring mitochondrial dysfunction and suppressing oxidative stress. Astonishingly, transcriptome analysis further reveals the role of GCA-CD in dampening cuproptosis through inhibiting FDX1/LIAS signaling pathway, highlighting the multifaceted therapeutic effects of the co-assembly in PD. The findings in this study underscore the comprehensive exposition on the actual function mechanisms of the therapeutic agents, thereby providing valuable insights for informing material design.

The Role of N6-Methyladenosine (m6A) RNA Modification in the Pathogenesis of Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative disease with a high prevalence among the middle-aged and elderly population. The pathogenesis of PD is closely linked to the misfolding and aggregation of α-synuclein, which contributes to the formation of Lewy bodies. These processes are associated with the degeneration of dopaminergic neurons, a key neuropathological change that underlies the motor symptoms of PD. In addition, genetic susceptibility, mitochondrial dysfunction, oxidative stress and neuroinflammation are involved in the progress of the disease. Previous studies indicated that the dysregulation of epigenetic modifications, including DNA methylation and histone acetylation, may be the key pathophysiological factors in PD. N6-methyladenosine (m6A) is a dynamically reversible modification in eukaryotes RNA, and could regulate mRNA degradation, stability, maturation, and translation. Recently, clinical research has shown that the global m6A level is significantly reduced in PD patients as well as the expression changes in m6A-associated proteins. Moreover, the dysregulation of m6A modification was shown to impact dopamine metabolism and damage dopaminergic neurons, indicating that m6A RNA modification may play a critical role in the pathogenesis of PD. In this review, we summarize recent clinical studies on m6A RNA modification in PD patients and discuss the regulatory role of m6A modification in dopamine metabolism and dopaminergic neurons death. Furthermore, based on the different m6A modification databases and prediction websites, we analyzed the potential m6A modification sites on the mRNA of key PD pathogenic genes (SNCA, PRKN, PINK1, and LRRK2) for the first time, aiming to offer new gene targets and perspectives understanding the pathogenesis of PD.

Mitochondrial stress disassembles nuclear architecture through proteolytic activation of PKCδ and Lamin B1 phosphorylation in neuronal cells: implications for pathogenesis of age-related neurodegenerative diseases

Mitochondrial dysfunction and oxidative stress are central to the pathogenesis of neurodegenerative diseases, including Parkinson's, Alzheimer's and Huntington's diseases. Neurons, particularly dopaminergic (DAergic) ones, are highly vulnerable to mitochondrial stress; however, the cellular and molecular mechanisms underlying this vulnerability remain poorly understood. Previously, we demonstrated that protein kinase C delta (PKCδ) is highly expressed in DAergic neurons and mediates apoptotic cell death during neurotoxic stress via caspase-3-mediated proteolytic activation. Herein, we further uncovered a key downstream molecular event of PKCδ signaling following mitochondrial dysfunction that governs neuronal cell death by dissembling nuclear architecture. Exposing N27 DAergic cells to the mitochondrial complex-1 inhibitor tebufenpyrad (Tebu) induced PKCδ phosphorylation at the T505 activation loop accompanied by caspase-3-dependent proteolytic activation. High-resolution 3D confocal microscopy revealed that proteolytically activated cleaved PKCδ translocates to the nucleus, colocalizing with Lamin B1. Electron microscopy also visualized nuclear membrane damage in Tebu-treated N27 cells. In silico analyses identified threonine site on Lamin B1 (T575) as a phosphorylation site of PKCδ. Interestingly, N27 DAergic cells stably expressing a PKCδ cleavage-resistant mutant failed to induce nuclear damage, PKCδ activation, and Lamin B1 phosphorylation. Furthermore, CRISPR/Cas9-based stable knockdown of PKCδ greatly attenuated Tebu-induced Lamin B1 phosphorylation. Also, studies using the Lamin B1T575G phosphorylation mutant and PKCδ-ΔNLS-overexpressing N27 cells showed that PKCδ activation and translocation to the nuclear membrane are essential for phosphorylating Lamin B1 at T575 to induce nuclear membrane damage during Tebu insult. Additionally, Tebu failed to induce Lamin B1 damage and Lamin B1 phosphorylation in organotypic midbrain slices cultured from PKCδ-/- mouse pups. Postmortem analyses of PD brains revealed significantly higher PKCδ activation, Lamin B1 phosphorylation, and Lamin B1 loss in nigral DAergic neurons compared to age-matched healthy controls, demonstrating the translational relevance of these findings. Collectively, our data reveal that PKCδ functions as a Lamin B1 kinase to disassemble the nuclear membrane during mitochondrial stress-induced neuronal death. This mechanistic insight may have important implications for the etiology of age-related neurodegenerative diseases resulting from mitochondrial dysfunction as well as for the development of novel treatment strategies.

The interplay between α-synuclein aggregation and necroptosis in Parkinson's disease: a spatiotemporal perspective

Parkinson's disease (PD) is a common neurodegenerative disorder characterized by the death of dopaminergic neurons and the aggregation of alpha-synuclein (α-Syn). It presents with prominent motor symptoms, and by the time of diagnosis, a significant number of neurons have already been lost. Current medications can only alleviate symptoms but cannot halt disease progression. Studies have confirmed that both dopaminergic neuronal loss and α-Syn aggregation are associated with necroptosis mechanisms. Necroptosis, a regulated form of cell death, has been recognized as an underexplored hotspot in PD pathogenesis research. In this review, we propose a spatiotemporal model of PD progression, highlighting the interactions between α-Syn aggregation, mitochondrial dysfunction, oxidative stress, neuroinflammation and necroptosis. These processes not only drive motor symptoms but also contribute to early non-motor symptoms, offering insights into potential diagnostic markers. Finally, we touch upon the therapeutic potential of necroptosis inhibition in enhancing current PD treatments, such as L-Dopa. This review aims to provide a new perspective on the pathogenesis of PD and to identify avenues for the development of more effective therapeutic strategies.

An integrated wearable microfluidic biosensor for simultaneous detection of multiple biomarkers in sweat

Simultaneous detection of biomarkers in sweat is crucial for comprehensive health assessment and personalized monitoring. However, the low sweat secretion rate and low metabolite concentrations present challenges for developing non-invasive wearable sensors. This study aims to develop a flexible wearable biosensor for simultaneous detection of low-concentration biomarkers in sweat, enabling comprehensive health assessment. This study synthesized an innovative bimetallic tungstate Ag@Ag2WO4 and evaluated its performance for detecting uric acid (UA, 10-1000 μM), dopamine (DA, 3-500 μM), and tyrosine (Tyr, 5-1000 μM). The detection limits (LODs) for DA, UA, and Tyr sensors were 3.10 μM, 8.47 μM, and 4.17 μM, respectively, with relative standard deviations (RSDs) of 4.76 %, 2.66 %, and 3.51 %, respectively. Additionally, this study designed a hydrophilic microfluidic collection system inspired by bamboo leaf structures to enhance sweat collection efficiency. Validation studies demonstrated that the wearable biosensor effectively detects UA and TA in the sweat of volunteers. We believe this research could contribute to advancing personalized healthcare by improving the convenience and effectiveness of health monitoring technologies.

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.

Gut microbiota and microRNAs as biomarkers in Parkinson's disease: early identification, diagnostic and potential treatments

The gut microbiota can affect both the enteric and the central nervous system, influencing individuals and their brain regulation. In this work, different pieces of scientific evidence are discussed, showing the relationship between changes in the microbiota and neurocognitive deterioration, focussing on Parkinson's disease (PD). Other factors that may cause or contribute to PD aetiology are the interactions between environmental factors and genetic susceptibility. According to the existing literature, there are several methods for the identification of neurocognitive impairment in different neurological diseases. However, such methods do not allow early identification, and therefore, the possibility of using other types of more effective diagnostic biomarkers in PD has also been investigated. Since this disease is characterised by specific microRNA (miRNA) expression, and the gut microbiota is an important factor in both PD and miRNA expression, the aim of this review is thoroughly analysing the role of microbiota and microRNAs in PD development. In addition, the relationship between these two factors and potential treatments will be also discussed.

Deciphering shared molecular dysregulation across Parkinson's disease variants using a multi-modal network-based data integration and analysis

Parkinson's disease (PD) is a progressive neurodegenerative disorder with no effective treatment. Advances in neuroscience and systems biomedicine now enable the use of complex patient-specific in vitro disease models and cutting-edge computational tools for data integration, enhancing our understanding of complex PD mechanisms. To explore common biomedical features across monogenic PD forms, we developed a knowledge graph (KG) by integrating previously published high-content imaging and RNA sequencing data of PD patient-specific midbrain organoids harbouring LRRK2-G2019S, SNCA triplication, GBA-N370S or MIRO1-R272Q mutations with publicly available biological data. Furthermore, we generated a single-cell RNA sequencing dataset of midbrain organoids derived from idiopathic PD patients (IPD) to stratify IPD patients within the spectrum of monogenic forms of PD. Despite the high degree of PD heterogeneity, we found that common transcriptomic dysregulation in monogenic PD forms is reflected in glial cells of IPD patient midbrain organoids. In addition, dysregulation in ROBO signalling might be involved in shared pathophysiology between monogenic PD and IPD cases.

Dopamine Toxicity Induces ROS-Dependent Death of Murine Neuroblastoma Cells: Impact on the Interactions of Cofilin With UCHL1 and MMP9

The death of dopaminergic neurons, a hallmark event during Parkinson's disease (PD), leads to increased dopamine concentration in the neuronal micro-environment. Keeping this in mind, we intend to understand the impact of elevated dopamine concentration on molecular interactions among proteins and the stability of the neuronal cytoskeleton. We used differentiated N2A cells and exposed them to 100 µM DA for 24 h. Evaluations of cell death, measurement of the concentration of DA oxidation products and reactive oxygen species (ROS), conventional RT-PCR, western blotting, zymography, reverse zymography, co-immunoprecipitation, mitochondrial transmembrane potential, confocal imaging, and in-silico studies were performed thereon. We observed that a significant number of viable N2A cells underwent ROS-dependent apoptotic cell death under elevated media DA concentrations. An altered transcriptional pattern of alpha-synuclein, UCHL1, and cofilin genes and their respective gene products were also observed. The activity and expression of matrix metalloproteinases9 (MMP9), involved in neuro-inflammation, was enhanced upon DA-exposure. Further, DA exposure also led to degradation of actin cytoskeleton. In silico studies revealed that interactions of Cofilin with UCHL1 and MMP9 were altered in dopamine-rich microenvironment. This result was further validated by co-immunoprecipitation experiments. Collectively our observations with murine neuroblastoma cells suggest that DA toxicity alters interaction patterns among intracellular proteins and degrades neuronal cytoskeleton that finally leads to cell death. Our study unveils a new frontier in PD treatment by paving the way for the development of specific drugs targeting the DA altered protein interactions.

Toxin-Induced Animal Models of Parkinson's Disease

The debilitating motor symptoms of Parkinson's disease (PD) result primarily from the degenerative nigrostriatal dopaminergic pathway. To elucidate pathogenic mechanisms and evaluate therapeutic strategies for PD, numerous animal models have been developed. Understanding the strengths and limitations of these models can significantly impact the choice of model, experimental design, and data interpretation. Herein, we systematically review the literature over the past decade. Some models no longer serve the purpose of PD models. The primary objectives of this review are: First, to assist new investigators in navigating through available animal models and making appropriate selections based on the objective of the study. Emphasis will be placed on common toxin-induced murine models. And second, to provide an overview of basic technical requirements for assessing the nigrostriatal pathway's pathology, structure, and function.

Advanced nutraceutical approaches to Parkinson's disease: bridging nutrition and neuroprotection

Parkinson's disease (PD) is a neurodegenerative disorder marked by progressive motor symptoms, including tremors, bradykinesia, and postural instability. The disease is characterized by dopaminergic neuron degeneration in the substantia nigra, leading to cognitive decline and motor dysfunction. Dietary supplements, known as nutraceuticals, have numerous health and medical benefits for treating and preventing the disease. Nutraceuticals offer neuroprotection through several mechanisms, including iron chelation, modulation of the cell-signaling pathway, scavenging of superoxide radicals and ROS, and suppression of inflammation. This review highlights the therapeutic potential of nutraceuticals as a complementary approach to traditional pharmaceutical treatments. Nutritional supplements such as Coenzyme Q10, Lycopene, Resveratrol, and Omega-3 fatty acids offer neuroprotection by targeting alpha-synuclein misfolding, oxidative stress, mitochondrial dysfunction, and neuroinflammation, potentially reducing the disease progression and improving patients' quality of life.

Lysosome-Mitochondrial Crosstalk in Cellular Stress and Disease

The perception of lysosomes and mitochondria as entirely separate and independent entities that degrade material and produce ATP, respectively, has been challenged in recent years as not only more complex roles for both organelles, but also an unanticipated level of interdependence are being uncovered. Coupled lysosome and mitochondrial function and dysfunction involve complex crosstalk between the two organelles which goes beyond mitochondrial quality control and lysosome-mediated clearance of damaged mitochondria through mitophagy. Our understanding of crosstalk between these two essential metabolic organelles has been transformed by major advances in the field of membrane contact sites biology. We now know that membrane contact sites between lysosomes and mitochondria play central roles in inter-organelle communication. This importance of mitochondria-lysosome contacts (MLCs) in cellular homeostasis, evinced by the growing number of diseases that have been associated with their dysregulation, is starting to be appreciated. How MLCs are regulated and how their coordination with other pathways of lysosome-mitochondria crosstalk is achieved are the subjects of ongoing scrutiny, but this review explores the current understanding of the complex crosstalk governing the function of the two organelles and its impact on cellular stress and disease.

The interaction of tPA with NMDAR1 drives neuroinflammation and neurodegeneration in α-synuclein-mediated neurotoxicity

The thrombolytic protease tissue plasminogen activator (tPA) is expressed in the CNS, where it regulates diverse functions including neuronal plasticity, neuroinflammation, and blood-brain-barrier integrity. However, its role in different brain regions such as the substantia nigra (SN) is largely unexplored. In this study, we characterize tPA expression, activity, and localization in the SN using a combination of retrograde tracing and β-galactosidase tPA reporter mice. We further investigate tPA's potential role in SN pathology in an α-synuclein mouse model of Parkinson's disease (PD). To characterize the mechanism of tPA action in α-synuclein-mediated pathology in the SN and to identify possible therapeutic pathways, we performed RNA-seq analysis of the SN and used multiple transgenic mouse models. These included tPA deficient mice and two newly developed transgenic mice, a knock-in model expressing endogenous levels of proteolytically inactive tPA (tPA Ala-KI) and a second model overexpressing proteolytically inactive tPA (tPA Ala-BAC). Our findings show that striatal GABAergic neurons send tPA+ projections to dopaminergic (DA)-neurons in the SN and that tPA is released from SN-derived synaptosomes upon stimulation. We also found that tPA levels in the SN increased following α-synuclein overexpression. Importantly, tPA deficiency protects DA-neurons from degeneration, prevents behavioral deficits, and reduces microglia activation and T-cell infiltration induced by α-synuclein overexpression. RNA-seq analysis indicates that tPA in the SN is required for the upregulation of genes involved in the innate and adaptive immune responses induced by α-synuclein overexpression. Overexpression of α-synuclein in tPA Ala-KI mice, expressing only proteolytically inactive tPA, confirms that tPA-mediated neuroinflammation and neurodegeneration is independent of its proteolytic activity. Moreover, overexpression of proteolytically inactive tPA in tPA Ala-BAC mice leads to increased neuroinflammation and neurodegeneration compared to mice expressing normal levels of tPA, suggesting a tPA dose response. Finally, treatment of mice with glunomab, a neutralizing antibody that selectively blocks tPA binding to the N-methyl-D-aspartate receptor-1 (NMDAR1) without affecting NMDAR1 ion channel function, identifies the tPA interaction with NMDAR1 as necessary for tPA-mediated neuroinflammation and neurodegeneration in response to α-synuclein-mediated neurotoxicity. Thus, our data identifies a novel pathway that promotes DA-neuron degeneration and suggests a potential therapeutic intervention for PD targeting the tPA-NMDAR1 interaction.

A Review on Therapeutic Strategies against Parkinson's Disease: Current Trends and Future Perspectives

Parkinson's Disease (PD) is the most common neurodegenerative disorder after Alzheimer's Disease and is clinically expressed by movement disorders, such as tremor, bradykinesia, and rigidity. It occurs mainly in the extrapyramidal system of the brain and is characterized by dopaminergic neuron degeneration. L-DOPA, dopaminergic agonists, anticholinergic drugs, and MAO-B inhibitors are currently used as therapeutic agents against PD, however, they have only symptomatic efficacy, mainly due to the complex pathophysiology of the disease. This review summarizes the main aspects of PD pathology, as well as, discusses the most important biochemical dysfunctions during PD, and presents novel multi-targeting compounds, which have been tested for their activity against various targets related to PD. This review selects various research articles from main databases concerning multi-targeting compounds against PD. Molecules targeting more than one biochemical pathway involved in PD, expected to be more effective than the current treatment options, are discussed. A great number of research groups have designed novel compounds following the multi-targeting drug approach. They include structures combining antioxidant, antiinflammatory, and metal-chelating properties. These compounds could be proven useful for effective multi-targeted PD treatment. Multi-targeting drugs could be a useful tool for the design of effective antiparkinson agents. Their efficacy towards various targets implicated in PD could be the key to the radical treatment of this neurodegenerative disorder.

The autophagy-lysosome pathway: a potential target in the chemical and gene therapeutic strategies for Parkinson's disease

Parkinson's disease is a common neurodegenerative disease with movement disorders associated with the intracytoplasmic deposition of aggregate proteins such as α-synuclein in neurons. As one of the major intracellular degradation pathways, the autophagy-lysosome pathway plays an important role in eliminating these proteins. Accumulating evidence has shown that upregulation of the autophagy-lysosome pathway may contribute to the clearance of α-synuclein aggregates and protect against degeneration of dopaminergic neurons in Parkinson's disease. Moreover, multiple genes associated with the pathogenesis of Parkinson's disease are intimately linked to alterations in the autophagy-lysosome pathway. Thus, this pathway appears to be a promising therapeutic target for treatment of Parkinson's disease. In this review, we briefly introduce the machinery of autophagy. Then, we provide a description of the effects of Parkinson's disease-related genes on the autophagy-lysosome pathway. Finally, we highlight the potential chemical and genetic therapeutic strategies targeting the autophagy-lysosome pathway and their applications in Parkinson's disease.

Boundary Complexity of (Sub-) Cortical Areas Predict Deep Brain Stimulation Outcomes in Parkinson's Disease

While deep brain stimulation (DBS) remains an effective therapy for Parkinson's disease (PD), sources of variance in patient outcomes are still not fully understood, underscoring a need for better prognostic criteria. Here we leveraged routinely collected T1-weighted (T1-w) magnetic resonance imaging (MRI) data to derive patient-specific measures of brain structure and evaluate their usefulness in predicting changes in PD medications in response to DBS. Preoperative T1-w MRI data from 231 patients with PD were used to extract regional measures of fractal dimension (FD), sensitive to the structural complexities of cortical and subcortical areas. FD was validated as a biomarker of Parkinson's disease (PD) progression through comparison of patients with PD and healthy controls (HCs). This analysis revealed significant group differences in FD across nine brain regions which supports its utility as a marker of PD. We evaluated the impact of adding imaging features (FD) to a clinical model that included demographics and clinical parameters-age, sex, total number and location of DBS electrodes, and preoperative motor response to levodopa. This model aimed to explain variance and predict changes in medication following DBS. Regression analysis revealed that inclusion of the FD of distributed brain areas correlated with post-DBS reductions in medication burden, explaining an additional 13.6% of outcome variance (R2=0.388) compared to clinical features alone (R2=0.252). Hypergraph-based classification learning tasks achieved an area under the receiver operating characteristic curve of 0.64 when predicting with clinical features alone, versus 0.76 when combining clinical and imaging features. These findings demonstrate that PD effects on brain morphology linked to disease progression influence DBS outcomes. The work also highlights FD as a potentially useful imaging biomarker to enhance DBS candidate selection criteria for optimized treatment planning.

Parkinson Disease -Targeted Nanocapsules for Synergistic Treatment: Combining Dopamine Replacement and Neuroinflammation Mitigation

Parkinson's disease (PD) is characterized by dopamine (DA) neuron loss and neuroinflammation. This study develops carrier-free nanocapsules (NCs) for targeted delivery of DA and catalase (CAT) to the PD brain, addressing both DA depletion and neuroinflammation simultaneously. The NCs are engineered by DA and 4-formylphenylboronic acid co-loading with cRGD-modified CAT (CAT-cRGD) and surface-modifying with Angiopep-2 (Ang). Ang targets the blood-brain barrier (BBB), enhancing brain delivery, while cRGD targets upregulated integrin receptors in the PD-affected BBB. The NCs showed a 1.4-fold increase in parkinsonian brain targeting efficiency compared to normal mice. In PD mice models, NCs demonstrated a stable increase in learning and memory, enhanced locomotor activity, and improved motor coordination. DA supplementation significantly enhanced dopaminergic signaling, increasing DA levels 1.8- and 3.5-fold in the striatum and substantia nigra, respectively. Additionally, delivered CAT effectively reduced neuroinflammation by mitigating endoplasmic reticulum stress, slowing disease progression, and protecting DA from oxidation. This innovative approach using PD-targeted NCs represents a synergistic strategy for PD treatment, combining symptomatic relief with disease progression intervention.

Intranasal AdipoRon Mitigated Anxiety and Depression-Like Behaviors in 6-OHDA-Induced Parkinson 's Disease Rat Model: Going Beyond Motor Symptoms

Depression and anxiety are prevalent neuropsychiatric conditions among patients with Parkinson's disease (PD), which may manifest prior to motor symptoms. As levodopa, a prominent treatment for PD motor symptoms, provides few benefits for mood-related abnormalities, tackling non-motor symptoms is particularly important. AdipoRon (Ad), an adiponectin agonist, has demonstrated neuroprotective effects by suppressing neuroinflammatory responses and activating the AMPK/Sirt-1 signaling pathway. This study looked at the potential advantages and underlying mechanisms of intranasal Ad in a rat model of PD induced by 6-hydroxydopamine (6-OHDA). We found that Ad at doses of 1 and 10 µg for 21 days exhibited anxiolytic- and antidepressant effects in the open field (OF) test, elevated plus maze (EPM), sucrose splash test, and forced swimming test in a PD model caused by a unilateral 6-OHDA injection into the medial forebrain bundle (MFB). The Ad also lowered the levels of corticosterone in the blood, decreased inflammasome components (NLRP3, caspase 1, and IL-1β), and increased Sirt-1 protein levels in the prefrontal cortex (PFC) of PD rats. We conclude that Ad ameliorates anxious and depressive-like behaviors in the PD rat model through stimulating the AMPK/Sirt-1 signaling and blocking the NLRP3 inflammasome pathways in the PFC.

Hesperetin protects against rotenone-induced motor disability and neurotoxicity via the regulation of SIRT1/NLRP3 signaling

Rotenone is a pesticide that causes complex I inhibition and is widely known to induce motor disability and experimental Parkinson's disease (PD) in rodents. Evidence suggests a crucial role for sirtuin/nuclear factor-kappaB/nod-like receptor family, pyrin domain-containing 3 (SIRT1/NFκB/NLRP3) signaling and inflammation in PD and rotenone neurotoxicity. Hesperetin (C16H14O6) is a citrus flavonoid with documented anti-inflammatory activity. We investigated the value of hesperetin in delaying rotenone-induced PD in mice and the possible modulation of inflammatory burden. PD was induced in mice via rotenone injections. Groups were assigned as a vehicle, PD, or PD + hesperetin (50 or 100 mg/kg) and compared for the motor function, protein level (by ELISA), and gene expression (by real-time PCR) of the target proteins, histopathology, and immunohistochemistry for tyrosine hydroxylase enzyme. Hesperetin (50 or 100 mg/kg) alleviated the motor disability and the striatal dopamine level and decreased the expression of NLRP3 and NF-κB but increased SIRT1 expression (p < 0.05). Further, it enhanced the neural viability and significantly decreased neural degeneration in the substantia nigra, hippocampus, and cerebral cortex (p < 0.05). Taken together, we propose that hesperetin mediates its neuroprotective function via alleviating modulation of the SIRT1/NFκB/NLRP3 pathway. Therefore, hesperetin might delay the PD progression.

Isolation of Lessertiosides A and B and Other Metabolites from Lessertia frutescens and Their Neuroprotection Activity

Lessertia frutescens (synonym Sutherlandia frutescens) is an important South African medicinal plant used traditionally to treat different human pathologies and is considered an adaptogenic plant. This study sought to isolate compounds from the plant and determine their protective potentials using SH-SY5Y cells and MPP+ (1-methyl-4-phenylpyridinium) to mimic Parkinson's disease. The phytochemical analysis of a 70% aqueous methanolic extract of L. frutescens leaves resulted in the isolation and identification of 11 pure compounds (1-11), among which compounds 1 and 2 were identified as new metabolites. The new compounds were characterised using IR, UV, NMR, and HRESIMS and were given the trivial names lessertiosides A (1) and B (2). Additionally, the flavonoids 8-methoxyvestitol (7) and mucronulatol (8) were isolated for the first time from the plant. The biological actions show that the isolated compounds had negligible toxicity on SH-SY5Y cells and improved cell viability in the cells exposed to MPP+. Furthermore, as a mechanism of action, the compounds could sustain cellular ATP generation and prevent MPP+-induced apoptotic cell death. Our findings provide evidence for the neuroprotective properties of compounds isolated from L. frutescens in MPP+-induced neuronal damage for the first time and create an avenue for these compounds to be further investigated to elucidate their molecular targets.

E3 ubiquitin ligase TRIM31 alleviates dopaminergic neurodegeneration by promoting proteasomal degradation of VDAC1 in Parkinson's Disease model

Mitochondrial dysfunction plays a pivotal role in the pathogenesis of Parkinson's disease (PD). As a mitochondrial governor, voltage-dependent anion channel 1 (VDAC1) is critical for cell survival and death signals and implicated in neurodegenerative diseases. However, the mechanisms of VDAC1 regulation are poorly understood and the role of tripartite motif-containing protein 31 (TRIM31), an E3 ubiquitin ligase which is enriched in mitochondria, in PD remains unclear. In this study, we found that TRIM31-/- mice developed age associated motor defects and dopaminergic (DA) neurodegeneration spontaneously. In addition, TRIM31 was markedly reduced both in nigrostriatal region of PD mice induced by MPTP and in SH-SY5Y cells stimulated by MPP+. TRIM31 deficiency significantly aggravated DA neurotoxicity induced by MPTP. Mechanistically, TRIM31 interacted with VDAC1 and catalyzed the K48-linked polyubiquitination to degrade it through its E3 ubiquitin ligase activity. In conclusion, we demonstrated for the first time that TRIM31 served as an important regulator in DA neuronal homeostasis by facilitating VDAC1 degradation through the ubiquitin-proteasome pathway. Our study identified TRIM31 as a novel potential therapeutic target and pharmaceutical intervention to the interaction between TRIM31 and VDAC1 may provide a promising strategy for PD.

CBD's potential impact on Parkinson's disease: An updated overview

Background

Parkinson's disease (PD) is primarily known as a motor disorder; however, its debilitating non-motor symptoms have a significant impact on patients' quality of life. The current standard treatment, l-DOPA, is used to relieve motor symptoms, but prolonged use is often associated with severe side effects. This creates an urgent need for effective alternatives targeting both motor and non-motor symptoms.

Objectives

Over the past decade, Cannabis sativa and its cannabinoids have been widely studied across various health conditions. Among these compounds, cannabidiol (CBD), a non-psychoactive component, is garnering growing interest due to its multi-targeted pleiotropic properties. This work aims to provide a comprehensive overview of CBD's efficacy in PD.

Methods

This review compiles data on both motor and non-motor symptoms of PD, integrating results from preclinical animal studies and available clinical trials.

Results

Preclinical research has demonstrated promising results regarding CBD's potential benefits in PD; however, the total number of clinical trials is limited (with only seven studies to date), making it difficult to draw definitive conclusions on its efficacy.

Conclusions

While preclinical findings suggest that CBD may have therapeutic potential in PD, the limited number of clinical trials highlights the need for further research. This review emphasizes the gaps that need to be addressed in future studies to fully understand CBD's role in treating both motor and non-motor symptoms of PD.

Human midbrain organoids: a powerful tool for advanced Parkinson's disease modeling and therapy exploration

Parkinson's disease (PD) is a neurodegenerative disorder marked by the loss of dopaminergic neurons in the substantia nigra. Despite progress, the pathogenesis remains unclear. Human midbrain organoids (hMLOs) have emerged as a promising model for studying PD, drug screening, and potential treatments. This review discusses the development of hMLOs, their application in PD research, and current challenges in organoid construction, highlighting possible optimization strategies.

Unraveling the AKT/ERK cascade and its role in Parkinson disease

Parkinson disease represents a significant and growing burden on global healthcare systems, necessitating a deeper understanding of their underlying molecular mechanisms for the development of effective treatments. The AKT and ERK pathways play crucial roles in the disease, influencing multiple cellular pathways that support neuronal survival. Researchers have made notable progress in uncovering how these pathways are controlled by upstream kinases and how their downstream effects contribute to cell signalling. However, as we delve deeper into their intricacies, we encounter increasing complexity, compounded by the convergence of multiple signalling pathways. Many of their targets overlap with those of other kinases, and they not only affect specific substrates but also influence entire signalling networks. This review explores the intricate interplay of the AKT/ERK pathways with several other signalling cascades, including oxidative stress, endoplasmic reticulum stress, calcium homeostasis, inflammation, and autophagy, in the context of Parkinson disease. We discuss how dysregulation of these pathways contributes to disease progression and neuronal dysfunction, highlighting potential therapeutic targets for intervention. By elucidating the complex network of interactions between the AKT/ERK pathways and other signalling cascades, this review aims to provide insights into the pathogenesis of Parkinson disease and describe the development of novel therapeutic strategies.

Gut microbiota: the indispensable player in neurodegenerative diseases

As one of the most urgent social and health problems in the world, neurodegenerative diseases have always been of interest to researchers. However, the pathological mechanisms and therapeutic approaches are not achieved. In addition to the established roles of oxidative stress, inflammation and immune response, changes of gut microbiota are also closely related to the pathogenesis of neurodegenerative diseases. Gut microbiota is the central player of the gut-brain axis, the dynamic bidirectional communication pathway between gut microbiota and central nervous system, and emerging insights have confirmed its indispensability in the development of neurodegenerative diseases. In this review, we discuss the complex relationship between gut microbiota and the central nervous system from the perspective of the gut-brain axis; review the mechanism of microbiota for the modulation different neurodegenerative diseases and discuss how different dietary patterns affect neurodegenerative diseases via gut microbiota; and prospect the employment of gut microbiota in the therapeutic approach to those diseases. © 2024 Society of Chemical Industry.

A2AR antagonists triggered the AMPK/m-TOR autophagic pathway to reverse the calcium-dependent cell damage in 6-OHDA induced model of PD

Calcium dyshomeostasis, oxidative stress, autophagy and apoptosis are the pathogenesis of selective dopaminergic neuronal loss in Parkinson's disease (PD). Earlier, we reported that A2A R modulates IP3-dependent intracellular Ca2+ signalling via PKA. Moreover, A2A R antagonist has been reported to reduce oxidative stress and apoptosis in PD models, however intracellular Ca2+ ([Ca2+]i) dependent autophagy regulation in the 6-OHDA model of PD has not been explored. In the present study, we investigated the A2A R antagonists mediated neuroprotective effects in 6-OHDA-induced primary midbrain neuronal (PMN) cells and unilateral lesioned rat model of PD. 6-OHDA-induced oxidative stress (ROS and superoxide) and [Ca2+]i was measured using Fluo4AM, DCFDA and DHE dye respectively. Furthermore, autophagy was assessed by Western blot of p-m-TOR/mTOR, p-AMPK/AMPK, LC3I/II, Beclin and β-actin. Apoptosis was measured by Annexin V-APC-PI detection and Western blot of Bcl2, Bax, caspase3 and β-actin. Dopamine levels were measured by Dopamine ELISA kit and Western blot of tyrosine hydroxylase. Our results suggest that 6-OHDA-induced PMN cell death occurred due to the interruption of [Ca2+]i homeostasis, accompanied by activation of autophagy and apoptosis. A2A R antagonists prevented 6-OHDA-induced neuronal cell death by decreasing [Ca2+]i overload and oxidative stress. In addition, we found that A2A R antagonists upregulated mTOR phosphorylation and downregulated AMPK phosphorylation thereby reducing autophagy and apoptosis both in 6-OHDA induced PMN cells and 6-OHDA unilateral lesioned rat model. In conclusion, A2A R antagonists alleviated 6-OHDA toxicity by modulating [Ca2+]i signalling to inhibit autophagy mediated by the AMPK/mTOR pathway.

Activation of Piezo1 by intracranial hypertension induced neuronal apoptosis via activating hippo pathway

AIM

Most of the subarachnoid hemorrhage (SAH) patients experienced the symptom of severe headache caused by intracranial hypertension. Piezo1 is a mechanosensitive ion channel protein. This study aimed to investigate the effect of Piezo1 on neurons in response to intracranial hypertension.

METHODS

The SAH rat model was performed by the modified endovascular perforation method. Piezo1 inhibitor GsMTx4 was administered intraperitoneally after SAH induction. To investigate the underlying mechanism, the selective Piezo1 agonist Yoda1, Piezo1 shRNA, and MY-875 were administered via intracerebroventricular injection before SAH induction. In vitro, we designed a pressurizing device to exclusively explore the effect of Piezo1 activation on primary neurons. Neurons were pretreated with Piezo1 inhibition followed by intracranial hypertension treatment, and then apoptosis-related proteins were detected.

RESULTS

Piezo1 inhibition significantly attenuated neuronal apoptosis and improved the outcome of neurological deficits in rats after SAH. The Hippo pathway agonist MY-875 reversed the anti-apoptotic effects of Piezo1 knockdown. In vitro, intracranial hypertension mimicked by the pressurizing device induced Piezo1 expression, resulting in Hippo pathway activation and neuronal apoptosis. The Hippo pathway inhibitor Xmu-mp-1 attenuated Yoda1-induced neuronal apoptosis. In addition, the combination of hypertension and oxyhemoglobin treatment exacerbated neuronal apoptosis.

CONCLUSIONS

Intracranial hypertension induced Piezo1 expression, neuronal apoptosis, and the Hippo pathway activation; the Hippo signaling pathway is involved in Piezo1 activation-induced neuronal apoptosis in respond to intracranial hypertension. Primary neurons treated with intracranial hypertension and oxyhemoglobin together can better characterize the circumstance of SAH in vivo, which is contributed to construct an ideal in vitro SAH model.

Variant-specific effects of GBA1 mutations on dopaminergic neuron proteostasis

Glucocerebrosidase 1 (GBA1) mutations are the most important genetic risk factors for Parkinson's disease (PD). Clinically, mild (e.g., p.N370S) and severe (e.g., p.L444P and p.D409H) GBA1 mutations have different PD phenotypes, with differences in age at disease onset, progression, and the severity of motor and non-motor symptoms. We hypothesize that GBA1 mutations cause the accumulation of α-synuclein by affecting the cross-talk between cellular protein degradation mechanisms, leading to neurodegeneration. Accordingly, we tested whether mild and severe GBA1 mutations differentially affect the degradation of α-synuclein via the ubiquitin-proteasome system (UPS), chaperone-mediated autophagy (CMA), and macroautophagy and differentially cause accumulation and/or release of α-synuclein. Our results demonstrate that endoplasmic reticulum (ER) stress and total ubiquitination rates were significantly increased in cells with severe GBA1 mutations. CMA was found to be defective in induced pluripotent stem cell (iPSC)-derived dopaminergic neurons with mild GBA1 mutations, but not in those with severe GBA1 mutations. When examining macroautophagy, we observed reduced formation of autophagosomes in cells with the N370S and D409H GBA1 mutations and impairments in autophagosome-lysosome fusion in cells with the L444P GBA1 mutation. Accordingly, severe GBA1 mutations were found to trigger the accumulation and release of oligomeric α-synuclein in iPSC-derived dopaminergic neurons, primarily as a result of increased ER stress and defective macroautophagy, while mild GBA1 mutations affected CMA, which is mainly responsible for the degradation of the monomeric form of α-synuclein. Overall, our findings provide new insight into the molecular basis of the clinical variability in PD associated with different GBA1 mutations.

Key Lipoprotein Receptor Targeted Echinacoside-Liposomes Effective Against Parkinson's Disease in Mice Model

Introduction

Parkinson's disease (PD) is a common neurodegenerative disorder characterized by the degeneration of dopaminergic neurons in the substantia nigra. The precise molecular mechanisms underlying neuronal loss in PD remain unknown, and there are currently no effective treatments for PD-associated neurodegeneration. Echinacoside (ECH) is known for its neuroprotective effects, which include scavenging cellular reactive oxygen species and promoting mitochondrial fusion. However, the blood-brain barrier (BBB) limits the bioavailability of ECH in the brain, posing a significant challenge to its use in PD treatment.

Methods

We synthesized and characterized PEGylated ECH liposomes (ECH@Lip) and peptide angiopep-2 (ANG) modified liposomes (ECH@ANG-Lip). The density of ANG in ANG-Lip was optimized using bEnd.3 cells. The brain-targeting ability of the liposomes was assessed in vitro using a transwell BBB model and in vivo using an imaging system and LC-MS. We evaluated the enhanced neuroprotective properties of this formulation in a the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD model.

Results

The ECH@ANG-Lip demonstrated significantly higher whole-brain uptake compared to ECH@Lip and free ECH. Furthermore, ECH@ANG-Lip was more effective in mitigating MPTP-induced behavioral impairment, oxidative stress, dopamine depletion, and dopaminergic neuron death than both ECH@Lip and free ECH.

Conclusion

The formulation used in our study significantly enhanced the neuroprotective efficacy of ECH in the MPTP-induced PD model. Thus, ECH@ANG-Lip shows considerable potential for improving the bioavailability of ECH and providing neuroprotective effects in the brain.

DNA tetrahedral nanocages as a promising nanocarrier for dopamine delivery in neurological disorders

Dopamine is a neurotransmitter in the central nervous system that is essential for many bodily and mental processes, and a lack of it can cause Parkinson's disease. DNA tetrahedral (TD) nanocages are promising in bio-nanotechnology, especially as a nanocarrier. TD is highly programmable, biocompatible, and capable of cell differentiation and proliferation. It also has tissue and blood-brain barrier permeability, making it a powerful tool that could overcome potential barriers in treating neurological disorders. In this study, we used DNA TD as a carrier for dopamine to cells and zebrafish embryos. We investigated the mechanism of complexation between TD and dopamine hydrochloride using gel electrophoresis, fluorescence and circular dichroism (CD) spectroscopy, atomic force microscopy (AFM), and molecular dynamic (MD) simulation tools. Further, we demonstrate that these dopamine-loaded DNA TD nanostructures enhanced cellular uptake and differentiation ability in SH-SY5Y neuroblastoma cells. Furthermore, we extended the study to zebrafish embryos as a model organism to examine survival and uptake. The research provides valuable insights into the complexation mechanism and cellular uptake of dopamine-loaded DNA tetrahedral nanostructures, paving the way for further advancements in nanomedicine for Parkinson's disease and other neurological disorders.

Serum Levels of Plasminogen Activator Inhibitor-1 in Patients with Parkinson's Disease

OBJECTIVES

The aim of the study was to investigate serum plasminogen activator inhibitor-1 (PAI-1) levels of patients with Parkinson's disease (PD) and their relationship with clinical findings and treatment of disease.

METHODS

The study included 125 PD patients and 48 healthy controls. Patients have been taking effective dopaminergic treatment regularly. The clinical severity of parkinsonism was assessed using the Hoehn and Yahr (HY) staging scale and the Unified PD Rating Scale (UPDRS). PAI-1 level analysis was performed by enzyme-linked immunosorbent assay.

RESULTS

Patients with PD had significantly lower serum PAI-1 levels than healthy controls (p < 0.001). Correlations with clinical findings showed only a marginally positive correlation between serum PAI-1 and HY score (r = 0.170, p = 0.05). In contrast, no significant correlation was demonstrated with the UPDRS score or other clinical parameters.

CONCLUSION

This is the first comprehensive analysis of serum PAI-1 levels in patients with PD. The distribution of PAI-1 in PD appears to be complex. The study results implicate that the paradoxical effects of tissue plasminogen activator on the brain parenchyma can be important in the pathophysiology of PD. Future studies are needed to elucidate the role of fibrinolytic system components in PD.

NOX2-TRPM2 coupling promotes Zn2+ inhibition of complex III to exacerbate ROS production in a cellular model of Parkinson's disease

Reactive oxygen species (ROS) serve vital physiological functions, but aberrant ROS production contributes to numerous diseases. Unfortunately, therapeutic progress targeting pathogenic ROS has been hindered by the limited understanding of whether the mechanisms driving pathogenic ROS differ from those governing physiological ROS generation. To address this knowledge gap, we utilised a cellular model of Parkinson's disease (PD), as an exemplar of ROS-associated diseases. We exposed SH-SY5Y neuroblastoma cells to the PD-toxin, MPP+ (1-methyl-4-phenylpyridinium) and studied ROS upregulation leading to cell death, the primary cause of PD. We demonstrate: (1) MPP+ stimulates ROS production by raising cytoplasmic Ca2+ levels, rather than acting directly on mitochondria. (2) To raise the Ca2+, MPP+ co-stimulates NADPH oxidase-2 (NOX2) and the Transient Receptor Potential Melastatin2 (TRPM2) channel that form a positive feedback loop to support each other's function. (3) Ca2+ exacerbates mitochondrial ROS (mtROS) production not directly, but via Zn2+. (4) Zn2+ promotes electron escape from respiratory complexes, predominantly from complex III, to generate mtROS. These conclusions are drawn from data, wherein inhibition of TRPM2 and NOX2, chelation of Ca2+ and Zn2+, and prevention of electron escape from complexes -all abolished the ability of MPP+ to induce mtROS production and the associated cell death. Furthermore, calcium ionophore mimicked the effects of MPP+, while Zn2+ ionophore replicated the effects of both MPP+ and Ca2+. Thus, we unveil a previously unrecognized signalling circuit involving NOX2, TRPM2, Ca2+, Zn2+, and complex III that drives cytotoxic ROS production. This circuit lies dormant in healthy cells but is triggered by pathogenic insults and could therefore represent a safe therapeutic target for PD and other ROS-linked diseases.

Alpha Synuclein Toxicity and Non-Motor Parkinson's

Parkinson's disease (PD) is a common multisystem neurodegenerative disorder affecting 1% of the population over the age of 60 years. The main neuropathological features of PD are the loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and the presence of alpha synuclein (αSyn)-rich Lewy bodies both manifesting with classical motor signs. αSyn has emerged as a key protein in PD pathology as it can spread through synaptic networks to reach several anatomical regions of the body contributing to the appearance of non-motor symptoms (NMS) considered prevalent among individuals prior to PD diagnosis and persisting throughout the patient's life. NMS mainly includes loss of taste and smell, constipation, psychiatric disorders, dementia, impaired rapid eye movement (REM) sleep, urogenital dysfunction, and cardiovascular impairment. This review summarizes the more recent findings on the impact of αSyn deposits on several prodromal NMS and emphasizes the importance of early detection of αSyn toxic species in biofluids and peripheral biopsies as prospective biomarkers in PD.

Forward and backward spatial recall in Parkinson's disease and matched controls: A 1-year follow-up study

Patients with Parkinson's disease (PD) exhibit a domain-general visuospatial dysfunction; however, no previous study has examined changes over time in forward and backward spatial recall in PD against controls. To evaluate changes in short-term (STM) and working memory (WM) dysfunction in PD, the current study assessed performance on a computer-modified version of the Corsi Block-Tapping Test (forward and backward recall) at two-time points 1 year apart, while simultaneously exploring associations with potentially relevant demographic and clinical variables. We enrolled 38 patients with PD and 38 controls matched for age, sex, and Montreal Cognitive Assessment (MoCA) total scores. Linear mixed-effects models analyzed the primary measured variables (forward and backward scores). At baseline, the dysfunction effect sizes were as follows: forward recall (-0.45, 95% CI [-0.90, 0.01]) and backward recall (-0.26, 95% CI [-0.71, 0.19]). At follow-up, patients exhibited substantially greater difficulties in backward recall (-0.65, 95% CI [-1.18, -0.13]) compared to the baseline assessment, whereas the forward dysfunction effect size remained almost the same (-0.43, 95% CI [-0.94, 0.09]). Age (p = .005, f = 0.35) and total scores on MoCA (p = .017, f = 0.18), irrespective of group and recall condition, were significant predictors of spatial block scores. The pattern of dysfunction effect sizes indicates that, in contrast to forward recall, backward recall dysfunction in PD worsened 1-year after the baseline assessment, presumably reflecting the progression of PD-related visuospatial WM dysfunction.

The autoimmune response induced by α-synuclein peptides drives neuronal cell death and glial cell activation

Parkinson's disease (PD) is a progressive neurodegenerative disorder associated with the loss of dopaminergic neurons and neuroinflammation. Recent studies have identified a role of T cells in the pathogenesis of PD. Additionally, these studies suggested that α-synuclein (α-Syn) is related to abnormal T-cell responses and may act as an epitope and trigger autoimmune T-cell responses. However, it is unclear whether the α-Syn-mediated autoimmune response occurs and whether it is related to neuronal cell death and glial cell activation. In this study, we investigated the autoimmune T-cell response induced by α-Syn peptides and evaluated the neurotoxic effect of the α-Syn peptide-mediated autoimmune response. The immunization of mice with α-Syn peptides resulted in enhanced autoimmune responses, such as the peptide recall response, polarization toward Th1/Th17 cells, and regulatory T cell imbalance. Furthermore, the α-Syn autoimmune response led to the death of primary neurons cocultured with splenocytes. Treatment with conditioned media from α-Syn peptide-immunized splenocytes induced microglia and toxic A1-type astrocyte activation. Taken together, our results provide evidence of the potential role of the α-Syn-initiated autoimmune response and its contribution to neuronal cell death and glial cell activation.

A Computational Model of Deep Brain Stimulation for Parkinson's Disease Tremor and Bradykinesia

Parkinson's disease (PD) is a progressive neurological disorder that is typically characterized by a range of motor dysfunctions, and its impact extends beyond physical abnormalities into emotional well-being and cognitive symptoms. The loss of dopaminergic neurons in the substantia nigra pars compacta (SNc) leads to an array of dysfunctions in the functioning of the basal ganglia (BG) circuitry that manifests into PD. While active research is being carried out to find the root cause of SNc cell death, various therapeutic techniques are used to manage the symptoms of PD. The most common approach in managing the symptoms is replenishing the lost dopamine in the form of taking dopaminergic medications such as levodopa, despite its long-term complications. Another commonly used intervention for PD is deep brain stimulation (DBS). DBS is most commonly used when levodopa medication efficacy is reduced, and, in combination with levodopa medication, it helps reduce the required dosage of medication, prolonging the therapeutic effect. DBS is also a first choice option when motor complications such as dyskinesia emerge as a side effect of medication. Several studies have also reported that though DBS is found to be effective in suppressing severe motor symptoms such as tremors and rigidity, it has an adverse effect on cognitive capabilities. Henceforth, it is important to understand the exact mechanism of DBS in alleviating motor symptoms. A computational model of DBS stimulation for motor symptoms will offer great insights into understanding the mechanisms underlying DBS, and, along this line, in our current study, we modeled a cortico-basal ganglia circuitry of arm reaching, where we simulated healthy control (HC) and PD symptoms as well as the DBS effect on PD tremor and bradykinesia. Our modeling results reveal that PD tremors are more correlated with the theta band, while bradykinesia is more correlated with the beta band of the frequency spectrum of the local field potential (LFP) of the subthalamic nucleus (STN) neurons. With a DBS current of 220 pA, 130 Hz, and a 100 microsecond pulse-width, we could found the maximum therapeutic effect for the pathological dynamics simulated using our model using a set of parameter values. However, the exact DBS characteristics vary from patient to patient, and this can be further studied by exploring the model parameter space. This model can be extended to study different DBS targets and accommodate cognitive dynamics in the future to study the impact of DBS on cognitive symptoms and thereby optimize the parameters to produce optimal performance effects across modalities. Combining DBS with rehabilitation is another frontier where DBS can reduce symptoms such as tremors and rigidity, enabling patients to participate in their therapy. With DBS providing instant relief to patients, a combination of DBS and rehabilitation can enhance neural plasticity. One of the key motivations behind combining DBS with rehabilitation is to expect comparable results in motor performance even with milder DBS currents.

Neuroprotective effects of flavonoids: endoplasmic reticulum as the target

The incidence of neurological disorders, particularly age-related neurodegenerative pathologies, exhibits an alarming upward trend, while current pharmacological interventions seldom achieve curative outcomes. Despite their diverse clinical presentations, neurological diseases often share a common pathological thread: the aberrant accumulation of misfolded proteins within the endoplasmic reticulum (ER). This phenomenon, known as ER stress, arises when the cell's intrinsic quality control mechanisms fail to cope with the protein-folding burden. Consequently, misfolded proteins accumulate in the ER lumen, triggering a cascade of cellular stress responses. Recognizing this challenge, researchers have intensified their efforts over the past two decades to explore natural compounds that could potentially slow or even reverse these devastating pathologies. Flavonoids constitute a vast and heterogeneous class of plant polyphenols, with over 10,000 identified from diverse natural sources such as wines, vegetables, medicinal plants, and organic products. Flavonoids are generally divided into six different subclasses: anthocyanidins, flavanones, flavones, flavonols, isoflavones, and flavonols. The diverse family of flavonoids, featuring a common phenolic ring backbone adorned with varying hydroxyl groups and additional modifications, exerts its antioxidant activity by inhibiting the formation of ROS, as evidenced by research. Also, studies suggest that polyphenols such as flavonoids can regulate ER stress through apoptosis and autophagy. By understanding these mechanisms, we can unlock the potential of flavonoids as novel therapeutic agents for neurodegenerative disorders. Therefore, this review critically examines the literature exploring the modulatory effects of flavonoids on various steps of the ER stress in neurological disorders.

Rotenone Induces a Neuropathological Phenotype in Cholinergic-like Neurons Resembling Parkinson's Disease Dementia (PDD)

Parkinson's disease with dementia (PDD) is a neurological disorder that clinically and neuropathologically overlaps with Parkinson's disease (PD) and Alzheimer's disease (AD). Although it is assumed that alpha-synuclein ( α -Syn), amyloid beta (A β ), and the protein Tau might synergistically induce cholinergic neuronal degeneration, presently the pathological mechanism of PDD remains unclear. Therefore, it is essential to delve into the cellular and molecular aspects of this neurological entity to identify potential targets for prevention and treatment strategies. Cholinergic-like neurons (ChLNs) were exposed to rotenone (ROT, 10 μ M) for 24 h. ROT provokes loss of Δ Ψ m , generation of reactive oxygen species (ROS), phosphorylation of leucine-rich repeated kinase 2 (LRRK2 at Ser935) concomitantly with phosphorylation of α -synuclein ( α -Syn, Ser129), induces accumulation of intracellular A β (iA β ), oxidized DJ-1 (Cys106), as well as phosphorylation of TAU (Ser202/Thr205), increases the phosphorylation of c-JUN (Ser63/Ser73), and increases expression of proapoptotic proteins TP53, PUMA, and cleaved caspase 3 (CC3) in ChLNs. These neuropathological features resemble those reproduced in presenilin 1 (PSEN1) E280A ChLNs. Interestingly, anti-oxidant and anti-amyloid cannabidiol (CBD), JNK inhibitor SP600125 (SP), TP53 inhibitor pifithrin- α (PFT), and LRRK2 kinase inhibitor PF-06447475 (PF475) significantly diminish ROT-induced oxidative stress (OS), proteinaceous, and cell death markers in ChLNs compared to naïve ChLNs. In conclusion, ROT induces p- α -Syn, iA β , p-Tau, and cell death in ChLNs, recapitulating the neuropathology findings in PDD. Our report provides an excellent in vitro model to test for potential therapeutic strategies against PDD. Our data suggest that ROT induces a neuropathologic phenotype in ChLNs similar to that caused by the mutation PSEN1 E280A.

SNHG14 Elevates NFAT5 Expression Through Sequestering miR-375-3p to Promote MPP + -Induced Neuronal Apoptosis, Inflammation, and Oxidative Stress in Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the loss of dopaminergic neurons. LncRNA small nucleolar RNA host gene 14 (SNHG14) was found to promote neuron injury in PD. Here, we investigated the mechanisms of SNHG14 in PD process. In vivo or in vitro PD model was established by using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mice or 1-methyl-4-phenylpyridinium (MPP +)-stimulated SK-N-SH cells. The expression of genes and proteins was measured by qRT-PCR and Western blot. In vitro assays were conducted using ELISA, CCK-8, colony formation, EdU, flow cytometry, and Western blot assays, respectively. The oxidative stress was evaluated by determining the production of superoxide dismutase (SOD) and malondialdehyde (MDA). The direct interactions between miR-375-3p and NFAT5 (Nuclear factor of activated T-cells 5) or SNHG14 was verified using dual-luciferase reporter and RNA immunoprecipitation (RIP) assays. SNHG14 and NFAT5 were elevated, while miR-375-3p was decreased in MPTP-mediated PD mouse model and MPP + -induced SK-N-SH cells. Knockdown of SNHG14 or NFAT5, or overexpression of miR-375-3p reversed MPP + -induced neuronal apoptosis, inflammation, and oxidative stress. Mechanistically, SNHG14 directly bound to miR-375, which targeted NFAT5. Inhibition of miR-375-3p abolished the inhibitory activity of SNHG14 knockdown on MPP + -evoked neuronal damage. Besides that, NFAT5 up-regulation counteracted the effects of miR-375-3p on MPP + -mediated neuronal damage. SNHG14 contributed to MPP + -induced neuronal injury by miR-375/NFAT5 axis, suggesting a new insight into the pathogenesis of PD.

LRRK2 regulates ferroptosis through the system Xc-GSH-GPX4 pathway in the neuroinflammatory mechanism of Parkinson's disease

Parkinson's disease (PD) is the most prevalent neurodegenerative disorder. Neuroinflammation mediated by activated microglia and apoptosis of dopaminergic (DA) neurons in the midbrain are its primary pathological manifestations. Leucine-rich repeat protein kinase 2 (LRRK2) kinase has been observed to increase expression during neuroinflammation, however, the effect of LRRK2 on microglia activation remains poorly understood. In this study, we have established lipopolysaccharide (LPS) treated BV2 cells and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) models for both in vivo and in vitro investigation. Our data in vivo reveal that LRRK2 can promote microglia activation by regulating ferroptosis and activating nuclear factor-κB. Inhibition of LRRK2 expression effectively suppressed the LPS-induced pro-inflammatory cytokines and facilitated the secretion of neuroprotective factors. Importantly, by co-overexpressing LRRK2 and glutathione peroxidase 4 (GPX4), we identified the system Xc-GSH-GPX4 pathway as a crucial component in LRRK2-mediated microglial ferroptosis and inflammatory responses. Using a microglial culture supernatant (MCS) transfer model, we found that inhibiting LRRK2 or downregulating ferroptosis in BV2 cells prevented SH-SY5Y cell apoptosis. Additionally, we observed abundant expression of LRRK2 and P-P65 in the midbrain, which was elevated in the MPTP-induced PD model, along with microglia activation. LRRK2 and P-P65 expression inhibition with PF-06447475 attenuated microglia activation in the nigrostriatal dense part of MPTP-treated mice. Based on our findings, it is evident that LRRK2 plays a critical role in promoting the neuroinflammatory response during the pathogenesis of PD by regulating the system Xc-GSH-GPX4 pathway. Taken together, our data highlights the potential research and therapeutic value of targeting LRRK2 to regulate neuroinflammatory response in PD through ferroptosis.

The role of the brain renin-angiotensin system in Parkinson´s disease

The renin-angiotensin system (RAS) was classically considered a circulating hormonal system that regulates blood pressure. However, different tissues and organs, including the brain, have a local paracrine RAS. Mutual regulation between the dopaminergic system and RAS has been observed in several tissues. Dysregulation of these interactions leads to renal and cardiovascular diseases, as well as progression of dopaminergic neuron degeneration in a major brain center of dopamine/angiotensin interaction such as the nigrostriatal system. A decrease in the dopaminergic function induces upregulation of the angiotensin type-1 (AT1) receptor activity, leading to recovery of dopamine levels. However, AT1 receptor overactivity in dopaminergic neurons and microglial cells upregulates the cellular NADPH-oxidase-superoxide axis and Ca2+ release, which mediate several key events in oxidative stress, neuroinflammation, and α-synuclein aggregation, involved in Parkinson's disease (PD) pathogenesis. An intraneuronal antioxidative/anti-inflammatory RAS counteracts the effects of the pro-oxidative AT1 receptor overactivity. Consistent with this, an imbalance in RAS activity towards the pro-oxidative/pro-inflammatory AT1 receptor axis has been observed in the substantia nigra and striatum of several animal models of high vulnerability to dopaminergic degeneration. Interestingly, autoantibodies against angiotensin-converting enzyme 2 and AT1 receptors are increased in PD models and PD patients and contribute to blood-brain barrier (BBB) dysregulation and nigrostriatal pro-inflammatory RAS upregulation. Therapeutic strategies addressed to the modulation of brain RAS, by AT1 receptor blockers (ARBs) and/or activation of the antioxidative axis (AT2, Mas receptors), may be neuroprotective for individuals with a high risk of developing PD or in prodromal stages of PD to reduce progression of the disease.

Artificial intelligence in positive mental health: a narrative review

The paper reviews the entire spectrum of Artificial Intelligence (AI) in mental health and its positive role in mental health. AI has a huge number of promises to offer mental health care and this paper looks at multiple facets of the same. The paper first defines AI and its scope in the area of mental health. It then looks at various facets of AI like machine learning, supervised machine learning and unsupervised machine learning and other facets of AI. The role of AI in various psychiatric disorders like neurodegenerative disorders, intellectual disability and seizures are discussed along with the role of AI in awareness, diagnosis and intervention in mental health disorders. The role of AI in positive emotional regulation and its impact in schizophrenia, autism spectrum disorders and mood disorders is also highlighted. The article also discusses the limitations of AI based approaches and the need for AI based approaches in mental health to be culturally aware, with structured flexible algorithms and an awareness of biases that can arise in AI. The ethical issues that may arise with the use of AI in mental health are also visited.

Safety, Tolerability, and Pharmacokinetics of the Monoamine Oxidase B Inhibitor, HEC122505, and its Major Metabolite After Single- and Multiple- Ascending Dose, and Food Effect Study in Healthy Chinese Subjects

BACKGROUND AND OBJECTIVES

HEC122505 is a potent and selectively monoamine oxidase B inhibitor that is safe and well-tolerated in preclinical models of Parkinson's disease. The objectives of single ascending dose and multiple dose pharmacokinetic trials of HEC122505 oral tablets were to determine the safety and tolerability of HEC122505, and to examine the food effect on the pharmacokinetic parameters of HEC122505 and its major metabolite HEC129870.

METHODS

The phase I study (NCT04625361) consisted of three arms: single ascending dose study (5, 20, 50, 100, 200, 300 or 400 mg HEC122505 tablets or placebo), multiple ascending dose study (20, 50 or 100 mg HEC122505 tablets or placebo once daily), and food effect (100 mg HEC122505 tablets single dose after a high-fat, high-calorie meal). All subjects completed all trial arms and were analyzed as planned.

RESULTS

Pharmacokinetic analysis showed that HEC122505 rapidly absorbed with the time to peak plasma concentration (Tmax) ranged from 0.5 to 1.75 h. In addition, maximum plasma drug concentration (Cmax) and area under the plasma concentration-time curve (AUC) increased in a dose proportional manner. Food effect study showed that a high-fat, high-calorie meal had no significant effect on the pharmacokinetics of HEC122505 and its major metabolite HEC129870, suggesting that HEC122505 could be administered in both fasted and fed state in clinical trials. The subsequent multiple-dose study evaluated doses from 20 to 100 mg dose once daily for up to 8 days. HEC122505 reached steady state after approximately 5 days with a once daily dose. In these studies, all dose of HEC122505 was generally safe and well tolerated. No grade ≥ 3 drug related adverse events (AEs) occurred.

CONCLUSION

HEC122505 was generally safe and well tolerated in the single ascending dose (ranging from 5 to 400 mg) and multiple ascending dose (50 to 200 mg once daily doses) studies. All the drug related adverse events (AEs) were Grade ≤ 2. There were no deaths, no subjects discontinued the trial due to AEs, and there were no other serious AEs. The safety and pharmacokinetic profile support once daily administration of HEC122505.

The SH-SY5Y cell line: a valuable tool for Parkinson's disease drug discovery

INTRODUCTION

Owing to limited efficient treatment strategies for highly prevalent and distressing Parkinson's disease (PD), an impending need emerged for deciphering new modes and mechanisms for effective management. SH-SY5Y-based in vitro neuronal models have emerged as a new possibility for the elucidation of cellular and molecular processes in the pathogenesis of PD. SH-SY5Y cells are of human origin, adhered to catecholaminergic neuronal attributes, which consequences in imparting wide acceptance and significance to this model over conventional in vitro PD models for high-throughput screening of therapeutics.

AREAS COVERED

Herein, the authors review the SH-SY5Y cell line and its value to PD research. The authors also provide the reader with their expert perspectives on how these developments can lead to the development of new impactful therapeutics.

EXPERT OPINION

Encouraged by recent research on SH-SY5Y cell lines, it was envisaged that this in vitro model can serve as a primary model for assessing efficacy and toxicity of new therapeutics as well as for nanocarriers' capacity in delivering therapeutic agents across BBB. Considering the proximity with human neuronal environment as in pathogenic PD conditions, SH-SY5Y cell lines vindicated consistency and reproducibility in experimental results. Accordingly, exploitation of this standardized SH-SY5Y cell line can fast-track the drug discovery and development path for novel therapeutics.