REV-ERBα Mitigates Astrocyte Activation and Protects Dopaminergic Neurons from Damage.

Parkinson's disease (PD) is characterized by astrocyte activation and disruptions in circadian rhythm. Within the astrocyte population, two distinct reactive states exist: A1 and A2. A1 astrocytes are associated with neurotoxicity and inflammation, while A2 astrocytes exhibit neuroprotective functions. Our investigation focused on the role of REV-ERBα, a member of the nuclear receptor superfamily and a key regulator of the circadian clock, in astrocyte activation. We observed that REV-ERBα expression in A1 astrocytes was reduced to one-third of its normal level. Notably, activation of REV-ERBα prompted a transformation of astrocytes from A1 to A2. Mechanistically, REV-ERBα inhibition was linked to the classical NF-κB pathway, while it concurrently suppressed the STAT3 pathway. Furthermore, astrocytes with low REV-ERBα expression were associated with dopaminergic neurons apoptosis. Intriguingly, the opposite effect was observed when using a REV-ERBα agonist, which mitigated astrocyte activation and reduced dopaminergic neuron damage by 50%. In summary, our study elucidates the pivotal role of REV-ERBα in modulating astrocyte function and its potential implications in PD pathogenesis.

Proteome dynamics in iPSC-derived human dopaminergic neurons.

Dopaminergic neurons participate in fundamental physiological processes and are the cell type primarily affected in Parkinson's disease. Their analysis is challenging due to the intricate nature of their function, involvement in diverse neurological processes, heterogeneity and localization in deep brain regions. Consequently, most of the research on the protein dynamics of dopaminergic neurons has been performed in animal cells ex vivo. Here we use iPSC-derived human mid-brain specific dopaminergic neurons to study general features of their proteome biology and provide datasets for protein turnover and dynamics, including a human axonal translatome. We cover the proteome to a depth of 9,409 proteins and use dynamic SILAC to measure the half-life of more than 4,300 proteins. We report uniform turnover rates of conserved cytosolic protein complexes such as the proteasome and map the variable rates of turnover of the respiratory chain complexes in these cells. We use differential dynamic SILAC labeling in combination with microfluidic devices to analyze local protein synthesis and transport between axons and soma. We report 105 potentially novel axonal markers and detect translocation of 269 proteins between axons and the soma in the time frame of our analysis (120 hours). Importantly, we provide evidence for local synthesis of 154 proteins in the axon and their retrograde transport to the soma, among them several proteins involved in RNA editing such as ADAR1 and the RNA helicase DHX30, involved in the assembly of mitochondrial ribosomes. Our study provides a workflow and resource for future applications of quantitative proteomics in iPSC-derived human neurons.

Absence of motor impairments or pathological changes in TMEM230 knockout rats.

Parkinson's disease (PD), which is the second most common neurodegenerative disorder, is characterized by progressive movement impairment and loss of midbrain dopaminergic neurons in the substantia nigra. Although mutations in TMEM230 are linked to familial PD, the pathogenic mechanism underlying TMEM230-associated PD remains to be elucidated. To explore the effect of TMEM230 depletion in vivo, we created TMEM230 knockout rats using CRISPR-Cas9 technology. TMEM230 knockout rats did not exhibit any core features of PD, including impaired motor function, loss of dopaminergic neurons in the substantia nigra, or altered expression of proteins related to autophagy, the Rab family, or vesicular trafficking. In addition, no glial reactions were observed in TMEM230 knockout rats. These results indicate that depletion of TMEM230 may not lead to dopaminergic neuron degeneration in rats, further supporting that PD-associated TMEM230 mutations lead to dopaminergic neuron death by gain-of-toxic function.

Treating activated regulatory T cells with pramipexole protects human dopaminergic neurons from 6-OHDA-induced degeneration.

BACKGROUND: Parkinson's disease (PD) is a chronic neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra, which promotes a sustained inflammatory environment in the central nervous system. Regulatory T cells (Tregs) play an important role in the control of inflammation and might play a neuroprotective role. Indeed, a decrease in Treg number and function has been reported in PD. In this context, pramipexole, a dopaminergic receptor agonist used to treat PD symptoms, has been shown to increase peripheral levels of Treg cells and improve their suppressive function. The aim of this work was to determine the effect of pramipexole on immunoregulatory Treg cells and its possible neuroprotective effect on human dopaminergic neurons differentiated from human embryonic stem cells. METHODS: Treg cells were sorted from white blood cells of healthy human donors. Assays were performed with CD3/CD28-activated and non-activated Treg cells treated with pramipexole at concentrations of 2 or 200 ng/mL. These regulatory cells were co-cultured with in vitro-differentiated human dopaminergic neurons in a cytotoxicity assay with 6-hydroxydopamine (6-OHDA). The role of interleukin-10 (IL-10) was investigated by co-culturing activated IL-10-producing Treg cells with neurons. To further investigate the effect of treatment on Tregs, gene expression in pramipexole-treated, CD3/CD28-activated Treg cells was determined by Fluidigm analysis. RESULTS: Pramipexole-treated CD3/CD28-activated Treg cells showed significant protective effects on dopaminergic neurons when challenged with 6-OHDA. Pramipexole-treated activated Treg cells showed neuroprotective capacity through mechanisms involving IL-10 release and the activation of genes associated with regulation and neuroprotection. CONCLUSION: Anti-CD3/CD28-activated Treg cells protect dopaminergic neurons against 6-OHDA-induced damage. In addition, activated, IL-10-producing, pramipexole-treated Tregs also induced a neuroprotective effect, and the supernatants of these co-cultures promoted axonal growth. Pramipexole-treated, activated Tregs altered their gene expression in a concentration-dependent manner, and enhanced TGFß-related dopamine receptor regulation and immune-related pathways. These findings open new perspectives for the development of immunomodulatory therapies for the treatment of PD.

Treatment of Parkinson's disease model with human umbilical cord mesenchymal stem cell-derived exosomes loaded with BDNF.

AIMS: Parkinson's disease (PD) is a common neurodegenerative disease that has received widespread attention; however, current clinical treatments can only relieve its symptoms, and do not effectively protect dopaminergic neurons. The purpose of the present study was to investigate the therapeutic effects of human umbilical cord mesenchymal stem cell-derived exosomes loaded with brain-derived neurotrophic factor (BDNF-EXO) on PD models and to explore the underlying mechanisms of these effects. MAIN METHODS: 6-Hydroxydopamine was used to establish in vivo and in vitro PD models. Western blotting, flow cytometry, and immunofluorescence were used to detect the effects of BDNF-EXO on apoptosis and ferroptosis in SH-SY5Y cells. The in vivo biological distribution of BDNF-EXO was detected using a small animal imaging system, and dopaminergic neuron improvements in brain tissue were detected using western blotting, immunofluorescence, immunohistochemistry, and Nissl and Prussian blue staining. KEY FINDINGS: BDNF-EXO effectively suppressed 6-hydroxydopamine-induced apoptosis and ferroptosis in SH-SY5Y cells. Following intravenous administration, BDNF-EXO crossed the blood-brain barrier to reach afflicted brain regions in mice, leading to a notable enhancement in neuronal survival. Furthermore, BDNF-EXO modulated microtubule-associated protein 2 and phosphorylated tau expression, thereby promoting neuronal cytoskeletal stability. Additionally, BDNF-EXO bolstered cellular antioxidant defense mechanisms through the activation of the nuclear factor erythroid 2-related factor 2 signaling pathway, thereby conferring neuroprotection against damage. SIGNIFICANCE: The novel drug delivery system, BDNF-EXO, had substantial therapeutic effects in both in vivo and in vitro PD models, and may represent a new treatment strategy for PD.

Beta2-Adrenergic Suppression of Neuroinflammation in Treatment of Parkinsonism, with Relevance for Neurodegenerative and Neoplastic Disorders.

There is a preliminary record suggesting that ß2-adrenergic agonists may have therapeutic value in Parkinson's disease; recent studies have proposed a possible role of these agents in suppressing the formation of α-synuclein protein, a component of Lewy bodies. The present study focuses on the importance of the prototypical ß2-adrenergic agonist epinephrine in relation to the incidence of Parkinson's disease in humans, and its further investigation via synthetic selective ß2-receptor agonists, such as levalbuterol. Levalbuterol exerts significant anti-inflammatory activity, a property that may suppress cytokine-mediated degeneration of dopaminergic neurons and progression of Parkinsonism. In a completely novel finding, epinephrine and certain other adrenergic agents modeled in the Harvard/MIT Broad Institute genomic database, CLUE, demonstrated strong associations with the gene-expression signatures of anti-inflammatory glucocorticoids. This prompted in vivo confirmation in mice engrafted with human peripheral blood mononuclear cells (PBMCs). Upon toxic activation with mononuclear antibodies, levalbuterol inhibited (1) the release of the eosinophil attractant chemokine eotaxin-1, which is implicated in CNS and peripheral inflammatory disorders, (2) elaboration of the tumor-promoting angiogenic factor VEGFa, and (3) release of the pro-inflammatory cytokine IL-13 from activated PBMCs. These observations suggest possible translation to Parkinson's disease, other neurodegenerative syndromes, and malignancies, via several mechanisms.

Iron-sulfur cluster loss in mitochondrial CISD1 mediates PINK1 loss-of-function phenotypes.

Parkinson's disease (PD) is characterized by the progressive loss of dopaminergic neurons in the substantia nigra of the midbrain. Familial cases of PD are often caused by mutations of PTEN-induced kinase 1 (PINK1) and the ubiquitin ligase Parkin, both pivotal in maintaining mitochondrial quality control. CISD1, a homodimeric mitochondrial iron-sulfur-binding protein, is a major target of Parkin-mediated ubiquitination. We here discovered a heightened propensity of CISD1 to form dimers in Pink1 mutant flies and in dopaminergic neurons from PINK1 mutation patients. The dimer consists of two monomers that are covalently linked by a disulfide bridge. In this conformation CISD1 cannot coordinate the iron-sulfur cofactor. Overexpressing Cisd, the Drosophila ortholog of CISD1, and a mutant Cisd incapable of binding the iron-sulfur cluster in Drosophila reduced climbing ability and lifespan. This was more pronounced with mutant Cisd and aggravated in Pink1 mutant flies. Complete loss of Cisd, in contrast, rescued all detrimental effects of Pink1 mutation on climbing ability, wing posture, dopamine levels, lifespan, and mitochondrial ultrastructure. Our results suggest that Cisd, probably iron-depleted Cisd, operates downstream of Pink1 shedding light on PD pathophysiology and implicating CISD1 as a potential therapeutic target.

Parkinson's disease affects millions of people worldwide, causing progressively worse symptoms like stiffness, tremors and difficulty moving. These issues result from the death of neurons in the brain that produce the neurotransmitter dopamine. While most cases have no known cause, 10 to 15 per cent are due to inherited gene mutations. This includes mutations in the genes that code for the proteins PINK1 and Parkin which are essential for maintaining healthy mitochondria, the powerhouse of the cell. Mutations in this quality control system affect a protein called CISD1, which sits within the outer surface of the mitochondria. CISD1 contains a cluster of iron and sulfur ions, and is involved in regulating iron levels and mitochondrial energy production. However, its role in inherited cases of Parkinson's disease, particularly those related to mutations in PINK1 and Parkin, is poorly understood. To understand the impact of CISD1, Bitar et al. studied genetically modified fruit flies and dopamine-producing neurons from Parkinson's patients with PINK1 mutations. This revealed that losing PINK1 activity led to higher levels of CISD1 proteins which lacked the iron-sulfur cluster due to a bond forming between two CISD1 molecules. Reducing levels of the CISD1-equivalent protein in the flies helped to alleviate most of the symptoms caused by PINK1 and Parkin gene mutations, such as difficulties climbing and impaired wing posture. These findings suggest that iron-depleted CISD1 contributes to the symptoms associated with Parkinson's disease, underscoring its potential as a drug target. Drugs that target CISD1 already exist, which could ease the way for further research. Recent studies have shown that cases of Parkinson's related to mutations in PINK-1 share features with some non-inherited instances of the disease, suggesting that this approach could potentially benefit many patients.

Dopaminergic REST/NRSF is protective against manganese-induced neurotoxicity in mice.

Chronic exposure to elevated levels of manganese (Mn) may cause a neurological disorder referred to as manganism. The transcription factor REST is dysregulated in several neurodegenerative diseases, such as Alzheimer's disease and Parkinson's disease. REST upregulated tyrosine hydroxylase and induced protection against Mn toxicity in neuronal cultures. In the present study, we investigated if dopaminergic REST plays a critical role in protecting against Mn-induced toxicity in vivo using dopaminergic REST conditional knockout (REST-cKO) mice and REST loxP mice as wild-type (WT) controls. Restoration of REST in the substantia nigra (SN) with neuronal REST AAV vector infusion was performed to further support the role of REST in Mn toxicity. Mice were exposed to Mn (330 ug, intranasal, daily for 3 weeks), followed by behavioral tests and molecular biology experiments. Results showed that Mn decreased REST mRNA/protein levels in the SN-containing midbrain, as well as locomotor activity and motor coordination in WT mice, which were further decreased in REST-cKO. Mn-induced mitochondrial insults, such as impairment of fission/fusion and mitophagy, apoptosis, and oxidative stress, in the midbrain of WT mice were more pronounced in REST-cKO. However, REST restoration in the SN of REST cKO mice attenuated Mn-induced neurotoxicity. REST's molecular target for its protection is unclear, but REST attenuated Mn-induced mitochondrial dysregulation, indicating that it is a primary intracellular target for both Mn and REST. These novel findings suggest that dopaminergic REST in the nigrostriatal pathway is critical in protecting against Mn toxicity, underscoring REST as a potential therapeutic target for treating manganism.

Dopaminergic system and neurons: Role in multiple neurological diseases.

The dopaminergic system is a complex and powerful neurotransmitter system in the brain. It plays an important regulatory role in motivation, reward, cognition, and motor control. In recent decades, research in the field of the dopaminergic system and neurons has increased exponentially and is gradually becoming a point of intervention in the study and understanding of a wide range of neurological diseases related to human health. Studies have shown that the dopaminergic system and neurons are involved in the development of many neurological diseases (including, but not limited to Parkinson's disease, schizophrenia, depression, attention deficit hyperactivity disorder, etc.) and that dopaminergic neurons either have too much stress or too weak function in the dopaminergic system can lead to disease. Therefore, targeting dopaminergic neurons is considered key to treating these diseases. This article provides a comprehensive review of the dopaminergic system and neurons in terms of brain region distribution, physiological function and subtypes of dopaminergic neurons, as well as the role of the dopaminergic system and neurons in a variety of diseases.

Use of phytocanabinoids in animal models of Parkinson's disease: Systematic review.

This systematic review was carried out with the aim of evaluating the use of medicinal Cannabis for the treatment of Parkinson's disease in experimental models. Furthermore, we sought to understand the main intracellular mechanisms capable of promoting the effects of phytocannabinoids on motor disorders, neurodegeneration, neuroinflammation and oxidative stress. The experimental models were developed in mice, rats and marmosets. There was a predominance of using only males in relation to females; in three studies, the authors evaluated treatments in males and females. Drugs were used as inducers of Parkinson's disease: 6-hydroxydopamine (6-OHDA), 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), lipopolysaccharide (LPS), and rotenone. Substances capable of promoting catalepsy in animals were also used: haloperidol, L-nitro-N-arginine (L-NOARG), WIN55,212-2, and reserpine. The inducing agent was injected stereotaxically or intraperitoneally. The most commonly used treatments were cannabidiol (CBD), Delta-9-tetrahydrocannabinol (Δ-9 THC) and Delta-9-tetrahydrocannabivarin (Δ-9 THCV), administered intraperitoneally, orally, subcutaneously and intramuscularly. The use of phytocannabinoids improved locomotor activity and involuntary movement and reduced catalepsy. There was an improvement in the evaluation of dopaminergic neurons, while in relation to dopamine content, the treatment had no effect. Inflammation, microglial/astrocyte activation and oxidative stress were reduced after treatment with phytocannabinoids, the same was observed in the results of tests for allodynia and hyperalgesia.

Pharmacological mechanisms of puerarin in the treatment of Parkinson's disease: An overview.

Puerarin, a monomer of traditional Chinese medicine, is a key component of Pueraria radix. Both clinical and experimental researches demonstrated that puerarin has therapeutic effects on Parkinson's disease (PD). Puerarin's pharmacological mechanisms include: 1) Anti-apoptosis. Puerarin inhibits cell apoptosis through the phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)/protein kinase B (Akt) and c-Jun N-terminal kinase (JNK) signaling pathways. Puerarin also exerts a hormone-like effect against cell apoptosis; 2) Anti-oxidative stress injury. Puerarin inhibits the Nrf2 nuclear exclusion through the GSK-3ß/Fyn pathway to promote the Nrf2 accumulation in the nucleus, and then promotes the antioxidant synthesis through the Nrf2/ARE signaling pathway to protect against oxidative stress; 3) Neuroprotective effects by intervening in the ubiquitin-proteasome system (UPS) and autophagy-lysosomal pathway (ALP). Puerarin significantly enhances the activity of chaperone-mediated autophagy (CMA), which downregulates the expression of α-synuclein, reduces its accumulation, and thus improves the function of damaged neurons. Additionally, puerarin increases proteasome activity and decreases ubiquitin-binding proteins, thereby preventing toxic accumulation of intracellular proteins; 4) Alleviating inflammatory response. Puerarin inhibits the conversion of microglia to the M1 phenotype while inducing the transition of microglia to the M2 phenotype. Furthermore, puerarin promotes the secretion of anti-inflammatory factor and inhibits the expression of pro-inflammatory factors; 5) Increasing the levels of dopamine and its metabolites. Puerarin could increase the levels of dopamine, homovanillic acid (HVA) and 3,4-dihydroxyphenylacetic acid (DOPAC) in the striatum; 6) Promoting neurotrophic factor expression and neuronal repair. Puerarin increases the expression of glial cell-derived neurotrophic factor (GDNF), brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF), thereby exerting a neuroprotective effect. Moreover, the regulation of the gut microbiota by puerarin may be a potential mechanism for the treatment of PD. The current review discusses the molecular mechanisms of puerarin, which may provide insight into the active components of traditional Chinese medicine in the treatment of PD.

Patch and matrix striatonigral neurons differentially regulate locomotion.

The striatonigral neurons are known to promote locomotion1,2. These neurons reside in both the patch (also known as striosome) and matrix compartments of the dorsal striatum3-5. However, the specific contribution of patch and matrix striatonigral neurons to locomotion remain largely unexplored. Using molecular identifier Kringle-Containing Protein Marking the Eye and the Nose (Kremen1) and Calbidin (Calb1)6, we showed in mouse models that patch and matrix striatonigral neurons exert opposite influence on locomotion. While a reduction in neuronal activity in matrix striatonigral neurons precedes the cessation of locomotion, fiber photometry recording during self-paced movement revealed an unexpected increase of patch striatonigral neuron activity, indicating an inhibitory function. Indeed, optogenetic activation of patch striatonigral neurons suppressed locomotion, contrasting with the locomotion-promoting effect of matrix striatonigral neurons. Consistently, patch striatonigral neuron activation markedly inhibited dopamine release, whereas matrix striatonigral neuron activation initially promoted dopamine release. Moreover, the genetic deletion of inhibitory GABA-B receptor Gabbr1 in Aldehyde dehydrogenase 1A1-positive (ALDH1A1+) nigrostriatal dopaminergic neurons (DANs) completely abolished the locomotion-suppressing effect caused by activating patch striatonigral neurons. Together, our findings unravel a compartment-specific mechanism governing locomotion in the dorsal striatum, where patch striatonigral neurons suppress locomotion by inhibiting the activity of ALDH1A1+ nigrostriatal DANs.

Alternating bilateral sensory stimulation alleviates alcohol-induced conditioned place preference via a superior colliculus-VTA circuit.

Alcohol is the most widely used addictive substance, potentially leading to brain damage and genetic abnormalities. Despite its prevalence and associated risks, current treatments have yet to identify effective methods for reducing cravings and preventing relapse. In this study, we find that 4-Hz alternating bilateral sensory stimulation (ABS) effectively reduces ethanol-induced conditioned place preference (CPP) in male mice, while 4-Hz flash light does not exhibit therapeutic effects. Whole-brain c-Fos mapping demonstrates that 4-Hz ABS triggers notable activation in superior colliculus GABAergic neurons (SCGABA). SCGABA forms monosynaptic connections with ventral tegmental area dopaminergic neurons (VTADA), which is implicated in ethanol-induced CPP. Bidirectional chemogenetic manipulation of SC-VTA circuit either replicates or blocks the therapeutic effects of 4-Hz ABS on ethanol-induced CPP. These findings elucidate the role of SC-VTA circuit for alleviating ethanol-related CPP by 4-Hz ABS and point to a non-drug and non-invasive approach that might have potential for treating alcohol use disorder.

Neuroprotective potential of solanesol against tramadol induced zebrafish model of Parkinson's disease: insights from neurobehavioral, molecular, and neurochemical evidence.

Parkinson's disease (PD) is a prevalent neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and subsequent depletion of dopamine in the striatum. Solanesol, an alcohol that acts as a precursor to coenzyme Q10, possesses potential applications in managing neurological disorders with antioxidant, anti-inflammatory, and neuromodulatory potential. In this study, a zebrafish model was employed to investigate the effects of solanesol in tramadol induced PD like symptoms. Zebrafish were administered tramadol injections (50 mg/kg) over a 20-day period. Solanesol was administered at doses of 25, 50, and 100 mg/kg, three hours prior to tramadol administration from day 11 to day 20. Behavioral tests assessing motor coordination were conducted on a weekly basis using open field and novel diving tank apparatus. On day 21, the zebrafish were euthanized, and brain tissues were examined for markers of oxidative stress, inflammation, and neurotransmitters level. Chronic tramadol treatment resulted in motor impairment, reduced antioxidant enzyme levels, enhanced release of proinflammatory cytokines in the striatum, and disrupted neurotransmitter balance. However, solanesol administration mitigated these effects and exhibited a neuroprotective effect against neurodegenerative alterations in the zebrafish model of PD. This was evident through improvements in behavior, modulation of biochemical markers, attenuation of neuroinflammation, restoration of neurotransmitters level, and enhancement of mitochondrial activity. The histopathological study also confirmed that solanesol dose dependently restored neuronal cell density which confirmed its neuroprotective potential. Further investigations are required to elucidate the underlying mechanisms of solanesol neuroprotective effects and evaluate its efficacy in human patients.

Neuroprotective effects: Solanesol has shown significant neuroprotective effects in a zebrafish model of Parkinson's disease induced by chronic tramadol usage.Improved behavioral performance: Administration of solanesol resulted in improved motor coordination in the open field test (OFT) and novel diving apparatus in the tramadol-induced zebrafish model of PD.Decreased inflammation: Solanesol treatment significantly reduced pro-inflammatory cytokine levels in the tramadol-induced zebrafish model of PD, indicating its anti-inflammatory properties.Restored oxidative parameters: Solanesol administration restored oxidative stress parameters, as well as catecholamine and neurotransmitter levels in the tramadol-induced zebrafish model of PD.Histopathological improvement: Solanesol administration prevented histopathological alterations induced by tramadol, indicating its ability to protect against neuronal damage in the zebrafish model of PD.

Transcription Factor-Mediated Generation of Dopaminergic Neurons from Human iPSCs-A Comparison of Methods.

Dopaminergic neurons are the predominant brain cells affected in Parkinson's disease. With the limited availability of live human brain dopaminergic neurons to study pathological mechanisms of Parkinson's disease, dopaminergic neurons have been generated from human-skin-cell-derived induced pluripotent stem cells. Originally, induced pluripotent stem-cell-derived dopaminergic neurons were generated using small molecules. These neurons took more than two months to mature. However, the transcription-factor-mediated differentiation of induced pluripotent stem cells has revealed quicker and cheaper methods to generate dopaminergic neurons. In this study, we compared and contrasted three protocols to generate induced pluripotent stem-cell-derived dopaminergic neurons using transcription-factor-mediated directed differentiation. We deviated from the established protocols using lentivirus transduction to stably integrate different transcription factors into the AAVS1 safe harbour locus of induced pluripotent stem cells. We used different media compositions to generate more than 90% of neurons in the culture, out of which more than 85% of the neurons were dopaminergic neurons within three weeks. Therefore, from our comparative study, we reveal that a combination of transcription factors along with small molecule treatment may be required to generate a pure population of human dopaminergic neurons.

The efficacy and safety of gene therapy approaches in Parkinson's disease: A systematic review.

BACKGROUND: Parkinson's disease (PD) is a neurodegenerative disorder characterized by the progressive loss of dopaminergic neurons in the brain. Despite existing treatments, there remains an unmet need for therapies that can halt or reverse disease progression. Gene therapy has been tried and tested for a variety of illnesses, including PD. The goal of this systematic review is to assess gene therapy techniques' safety and effectiveness in PD clinical trials. METHODS: Online databases PubMed/Medline, and Cochrane were used to screen the studies for this systematic review. The risk of bias of the included studies was assessed using standard tools. RESULTS: Gene therapy can repair damaged dopaminergic neurons from the illness or deal with circuit anomalies in the basal ganglia connected to Parkinson's disease symptoms. Rather than only treating symptoms, this neuroprotective approach alters the illness itself. Medication for gene therapy is currently administered at the patient's bedside. It can hyperactivate specific brain circuits associated with motor dysfunction. PD therapies are developing quickly, and there aren't enough head-to-head trials evaluating the safety and effectiveness of available treatments. When choosing an advanced therapy, patient-specific factors should be considered in addition to the effectiveness and safety of each treatment option. CONCLUSION: In comparison to conventional therapies, gene therapy may be advantageous for PD. It may minimize side effects, relieve symptoms, and offer dependable dopamine replacement.

Alpha-Synuclein Gene Alterations Modulate Tyrosine Hydroxylase in Human iPSC-Derived Neurons in a Parkinson's Disease Animal Model.

Parkinson's disease (PD) caused by SNCA gene triplication (3XSNCA) leads to early onset, rapid progression, and often dementia. Understanding the impact of 3XSNCA and its absence is crucial. This study investigates the differentiation of human induced pluripotent stem cell (hiPSC)-derived floor-plate progenitors into dopaminergic neurons. Three different genotypes were evaluated in this study: patient-derived hiPSCs with 3XSNCA, a gene-edited isogenic line with a frame-shift mutation on all SNCA alleles (SNCA 4KO), and a normal wild-type control. Our aim was to assess how the substantia nigra pars compacta (SNpc) microenvironment, damaged by 6-hydroxydopamine (6-OHDA), influences tyrosine hydroxylase-positive (Th+) neuron differentiation in these genetic variations. This study confirms successful in vitro differentiation into neuronal lineage in all cell lines. However, the SNCA 4KO line showed unusual LIM homeobox transcription factor 1 alpha (Lmx1a) extranuclear distribution. Crucially, both 3XSNCA and SNCA 4KO lines had reduced Th+ neuron expression, despite initial successful neuronal differentiation after two months post-transplantation. This indicates that while the SNpc environment supports early neuronal survival, SNCA gene alterations-either amplification or knock-out-negatively impact Th+ dopaminergic neuron maturation. These findings highlight SNCA's critical role in PD and underscore the value of hiPSC models in studying neurodegenerative diseases.

Human amniotic epithelial stem cell-derived dopaminergic neuron-like cells ameliorate motor dysfunction in a rat model of Parkinson's disease.

AIMS: Parkinson's disease (PD) remains a substantial clinical challenge due to the progressive loss of midbrain dopaminergic (DA) neurons in nigrostriatal pathway. In this study, human amniotic epithelial stem cells (hAESCs)-derived dopaminergic neuron-like cells (hAESCs-DNLCs) were generated, with the aim of providing new therapeutic approach to PD. MATERIALS AND METHODS: hAESCs, which were isolated from discarded placentas, were induced to differentiate into hAESCs-DNLCs by following a "two stages" induction protocol. The differentiation efficiency was assessed by quantitative real-time PCR (qRT-PCR), immunocytochemistry (ICC), and ELISA. Immunogenicity, cell viability and tumorigenicity of hAESCs-DNLC were analyzed before in vivo experiments. Subsequently, hAESCs-DNLCs were transplanted into PD rats, behavioral tests were monitored after graft, and the regeneration of DA neurons was detected by immunohistochemistry (IHC). Furthermore, to trace hAESCs-DNLCs in vivo, cells were pre-labeled with PKH67 green fluorescence. KEY FINDINGS: hAESCs were positive for pluripotent markers and highly expressed neural stem cells (NSCs) markers. Based on this, we established an induction method reliably generates hAESCs-DNLCs, which was evidenced by epithelium-to-neuron morphological changes, elevated expressions of neuronal and DA neuronal markers, and increased secretion of dopamine. Moreover, hAESCs-DNLCs maintained high cell viability, no tumorigenicity and low immunogenicity, suggesting hAESCs-DNLCs an attractive implant for PD therapy. Transplantation of hAESCs-DNLCs into PD rats significantly ameliorated motor disorders, as well as enhanced the reinnervation of TH+ DA neurons in nigrostriatal pathway. SIGNIFICANCE: Our study has demonstrated evident therapeutic effects of hAESCs-DNLCs, and provides a safe and promising solution for PD.

Downregulation of Protease Cathepsin D and Upregulation of Pathologic α-Synuclein Mediate Paucity of DNAJC6-Induced Degeneration of Dopaminergic Neurons.

A homozygous mutation of the DNAJC6 gene causes autosomal recessive familial type 19 of Parkinson's disease (PARK19). To test the hypothesis that PARK19 DNAJC6 mutations induce the neurodegeneration of dopaminergic cells by reducing the protein expression of functional DNAJC6 and causing DNAJC6 paucity, an in vitro PARK19 model was constructed by using shRNA-mediated gene silencing of endogenous DANJC6 in differentiated human SH-SY5Y dopaminergic neurons. shRNA targeting DNAJC6 induced the neurodegeneration of dopaminergic cells. DNAJC6 paucity reduced the level of cytosolic clathrin heavy chain and the number of lysosomes in dopaminergic neurons. A DNAJC6 paucity-induced reduction in the lysosomal number downregulated the protein level of lysosomal protease cathepsin D and impaired macroautophagy, resulting in the upregulation of pathologic α-synuclein or phospho-α-synucleinSer129 in the endoplasmic reticulum (ER) and mitochondria. The expression of α-synuclein shRNA or cathepsin D blocked the DNAJC6 deficiency-evoked degeneration of dopaminergic cells. An increase in ER α-synuclein or phospho-α-synucleinSer129 caused by DNAJC6 paucity activated ER stress, the unfolded protein response and ER stress-triggered apoptotic signaling. The lack of DNAJC6-induced upregulation of mitochondrial α-synuclein depolarized the mitochondrial membrane potential and elevated the mitochondrial level of superoxide. The DNAJC6 paucity-evoked ER stress-related apoptotic cascade, mitochondrial malfunction and oxidative stress induced the degeneration of dopaminergic neurons via activating mitochondrial pro-apoptotic signaling. In contrast with the neuroprotective function of WT DNAJC6, the PARK19 DNAJC6 mutants (Q789X or R927G) failed to attenuate the tunicamycin- or rotenone-induced upregulation of pathologic α-synuclein and stimulation of apoptotic signaling. Our data suggest that PARK19 mutation-induced DNAJC6 paucity causes the degeneration of dopaminergic neurons via downregulating protease cathepsin D and upregulating neurotoxic α-synuclein. Our results also indicate that PARK19 mutation (Q789X or R927G) impairs the DNAJC6-mediated neuroprotective function.

TrueTH: A user-friendly deep learning approach for robust dopaminergic neuron detection.

Parkinson's disease (PD) entails the progressive loss of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNc), leading to movement-related impairments. Accurate assessment of DA neuron health is vital for research applications. Manual analysis, however, is laborious and subjective. To address this, we introduce TrueTH, a user-friendly and robust pipeline for unbiased quantification of DA neurons. Existing deep learning tools for tyrosine hydroxylase-positive (TH+) neuron counting often lack accessibility or require advanced programming skills. TrueTH bridges this gap by offering an open-sourced and user-friendly solution for PD research. We demonstrate TrueTH's performance across various PD rodent models, showcasing its accuracy and ease of use. TrueTH exhibits remarkable resilience to staining variations and extreme conditions, accurately identifying TH+ neurons even in lightly stained images and distinguishing brain section fragments from neurons. Furthermore, the evaluation of our pipeline's performance in segmenting fluorescence images shows strong correlation with ground truth and outperforms existing models in accuracy. In summary, TrueTH offers a user-friendly interface and is pretrained with a diverse range of images, providing a practical solution for DA neuron quantification in Parkinson's disease research.