Search Results (233)

Parkinson’s disease (PD) is a progressive, multisystemic α-synucleinopathy, recognized as the second most prevalent neurodegenerative disorder globally. Its neuropathology is characterized by the degeneration of dopaminergic neurons, particularly in the substantia nigra pars compacta (SNpc), and the intraneuronal accumulation of α-synuclein-forming Lewy bodies. Oxidative stress is a key contributor to PD pathogenesis. Thioredoxin-interacting protein (TXNIP) is a crucial regulator of cellular redox balance, inhibiting the antioxidant function of thioredoxin. This pilot study aimed to investigate the protein expression and localization of TXNIP in the SNpc of PD patients compared to healthy controls. We performed immunohistochemical analyses on 12 post-mortem human brain sections (formalin-fixed, paraffin-embedded) from six subjects with PD and six healthy controls. The study was performed on PD subjects with Braak stage 6. Our findings revealed that in control samples, TXNIP protein was distinctly and closely associated with neuromelanin (NM) pigment within the cytoplasm of SNpc dopaminergic neurons. Conversely, in PD samples, there was a markedly weak cytoplasmic expression of TXNIP, and critically, this association with NM pigment was absent. Furthermore, PD samples exhibited a significant reduction in both dopaminergic neurons and NM content, consistent with advanced disease. These findings, which mirror previous transcriptomic data showing TXNIP gene under-expression in the same subjects, suggest that altered TXNIP expression and localization in SNpc dopaminergic neurons are features of late-stage PD, potentially reflecting neuronal dysfunction and loss. Full article

Neuroinflammation driven by microglial activation and α-synuclein (αSyn) aggregation is one of the central features driving Parkinson’s disease (PD) pathogenesis. GM1 ganglioside’s oligosaccharide moiety (OligoGM1) has shown neuroprotective potential in PD neuronal models, but its direct effects on inflammation remain poorly defined. This study investigated the ability of OligoGM1 to modulate microglial activation and αSyn handling in a human in vitro model. Human embryonic microglial (HMC3) cells were exposed to αSyn pre-formed fibrils (PFFs) in the presence or absence of OligoGM1. Microglial activation markers, intracellular αSyn accumulation, and cytokine release were assessed by immunofluorescence and ELISA. OligoGM1 had no effect on microglial morphology or cytokine release under basal conditions. Upon αSyn challenge, cells exhibited increased amounts of ionized calcium-binding adaptor molecule 1 (Iba1), triggered receptor expressed on myeloid cells 2 (TREM2), elevated αSyn accumulation, and secreted pro-inflammatory cytokines. OligoGM1 pre-treatment significantly reduced the number and area of Iba1(+) cells, the intracellular αSyn burden in TREM2(+) microglia, and the release of interleukin 6 (IL-6). OligoGM1 selectively attenuated αSyn-induced microglial activation and enhanced αSyn clearance without compromising basal immune function. These findings confirm and support the potential of OligoGM1 as a multitarget therapeutic candidate for PD that is capable of modulating glial reactivity and neuroinflammatory responses. Full article

The fibrillary aggregation of α-synuclein is a hallmark of Parkinson’s disease (PD) and a potential target for diagnostics and therapeutics. Although substantial effort has been devoted to the development of positron emission tomography (PET) probes for detecting α-synuclein aggregates, no clinically suitable tracer has been reported. The design and synthesis of 43 new N-(6-methoxypyridin-3-yl)quinolin-2-amine derivatives and an evaluation of their α-synuclein binding affinity is reported here. Compounds 7f, 7j, and 8i exhibited high affinity for α-synuclein and were selected for ¹¹C, ¹⁸F, ¹²⁵I, or ³H radiolabeling. A photoaffinity variant, TZ-CLX, structurally related to 7j and 8i, demonstrated preferential binding to the C-terminal region of α-synuclein fibrils. PET brain imaging studies using [¹¹C]7f, [¹⁸F]7j, and [¹¹C]8i in non-human primates indicated that these three α-synuclein PET tracers penetrated the blood–brain barrier. Both [¹¹C]7f and [¹⁸F]7j showed more favorable brain washout pharmacokinetics than [¹¹C]8i. In vitro binding assays showed that [¹²⁵I]8i is a very potent α-synuclein radioligand, with K_d values of 5 nM for both PD brain tissues and LBD-amplified fibrils; it is also selective for PD tissues versus AD or control tissues. These results strongly suggest that the PET probes based on the N-(6-methoxypyridin-3-yl)quinoline-2-amine scaffold have potential utility in detecting α-synuclein aggregates in vivo. Full article

Parkinson’s disease (PD) is the second most prevalent neurodegenerative disease. It is characterized by mitochondrial dysfunction, increased reactive oxygen species (ROS), α-synuclein (α-syn) and phosphorylated-tau protein (p-tau) aggregation, and dopaminergic neuron cell death. Current drug therapies only provide temporary symptomatic relief and fail to stop or reverse disease progression due to the severe side effects or the blood–brain barrier. This study aimed to investigate the neuroprotective effects of an intermittent heating approach, thermal cycling-hyperthermia (TC-HT), in an in vitro PD model using rotenone (ROT)-induced human neural SH-SY5Y cells. Our results revealed that TC-HT pretreatment conferred neuroprotective effects in the ROT-induced in vitro PD model using human SH-SY5Y neuronal cells, including reducing ROT-induced mitochondrial apoptosis and ROS accumulation in SH-SY5Y cells. In addition, TC-HT also inhibited the expression of α-syn and p-tau through heat-activated pathways associated with sirtuin 1 (SIRT1) and heat-shock protein 70 (Hsp70), involved in protein chaperoning, and resulted in the phosphorylation of Akt and glycogen synthase kinase-3β (GSK-3β), which inhibit p-tau formation. These findings underscore the potential of TC-HT as an effective treatment for PD in vitro, supporting its further investigation in in vivo models with focused ultrasound (FUS) as a feasible heat-delivery approach. Full article

Pathological aggregation of α-synuclein (αS) is implicated in the pathogenesis of Parkinson’s disease (PD) and other α-synucleinopathies. The current view is that neuron-to-neuron spreading of αS pathology contributes to the progression of α-synucleinopathy. We used an A53T mutant human αS transgenic mouse model (TgA53T) to examine whether the site of pathogenic αS inoculation affects the pattern of neuropathology and whether soluble and insoluble fractions derived from crude pathogenic tissue lysates exhibit differential capacities to initiate αS pathology. To test whether the inoculation site impacts the ultimate spatial/temporal patterns of αS pathology, αS preformed fibrils (PFFs), or brain homogenates from TgA53T mice with α-synucleinopathy, were injected into the cortex/striatum, brainstem, or skeletal muscle. In all cases, inoculation of pathogenic αS induced end-stage motor dysfunction within ~100 days post-inoculation (dpi). Significantly, irrespective of the inoculation sites, the ultimate distribution of the αS pathology was like that seen in normally aged TgA53T mice at end-stage, indicating that the intrinsic neuronal vulnerability is a significant determinant in the induction of αS pathology, even when initiated by inoculation of pathogenic αS. Temporal analysis of brainstem-injected TgA53T mice show that initial αS pathology was seen by 30 days post-inoculation and inflammatory changes occur at later stages. In addition, we show that both highly soluble (S150) and insoluble (P150) fractions from end-stage TgA53T mice can seed de novo αS pathology in vivo. Moreover, the endoplasmic reticulum (ER)-enriched fraction from the TgA53T mice were highly pathogenic as the ER fraction induced αS pathology faster than other fractions when injected unilaterally into TgA53T mice. Our results suggest that multiple αS species from the brain can initiate the development of progressive αS pathology. Full article

Heterozygous mutations in the GBA1 gene, encoding the enzyme glucocerebrosidase (GCase), are major risk factors for Parkinson’s Disease (PD). Ambroxol, a small chaperone originally used as a mucolytic agent, has been shown to cross the blood–brain barrier, enhance GCase activity, and reduce α-synuclein levels, making it a promising therapeutic candidate for disease-modifying effects in GBA1-associated PD (GBA1-PD). This study aimed to develop a method to quantify ambroxol levels in human plasma and cerebrospinal fluid (CSF) using liquid chromatography–tandem mass spectrometry (LC-MS/MS). Ambroxol was determined by online solid-phase extraction (SPE), coupled with LC-MS/MS, by gradient elution on a monolithic column. Detection employed a 3200 QTRAP tandem mass spectrometer in the positive electrospray ionization mode. Calibration curves exhibited linearity across the analyzed ranges in both plasma and CSF. The recovery rate ranged from 106.7% to 113.5% in plasma and from 99.0% to 103.0% in CSF. No significant matrix effect was observed. Intra-day and inter-day precisions were below 11.8% in both matrices, and accuracy ranged from 89.9% to 103.1% in plasma and from 96.3% to 107.8% in CSF. We evaluated and confirmed the stability of the analyte in plasma and CSF across various storage conditions. The method was successfully validated according to European Medicine Agency (EMA) guidelines and its applicability was confirmed in the context of a multicenter, randomized, double-blind, placebo-controlled, phase II study, designed to monitor the ambroxol levels in the plasma and CSF of GBA1-PD. Full article

Parkinson’s disease (PD) is a progressive neurodegenerative disorder marked by the degeneration of dopaminergic neurons in the substantia nigra, leading to decreased dopamine levels in the striatum and causing a range of motor and non-motor impairments. Although the molecular mechanisms driving PD progression remain incompletely understood, emerging evidence suggests that the buildup of nuclear DNA damage, especially DNA double-strand breaks (DDSBs), plays a key role in contributing neurodegeneration, promoting senescence and neuroinflammation. Despite the pathogenic role for DDSB in neurodegenerative disease, targeting DNA repair mechanisms in PD is largely unexplored as a therapeutic approach. Ataxia telangiectasia mutated (ATM), a key kinase in the DNA damage response (DDR), plays a crucial role in neurodegeneration. In this study, we evaluated the therapeutic potential of AZD1390, a highly selective and brain-penetrant ATM inhibitor, in reducing neuroinflammation and improving behavioral outcomes in a mouse model of α-synucleinopathy. Four-month-old C57BL/6J mice were unilaterally injected with either an empty AAV1/2 vector (control) or AAV1/2 expressing human A53T α-synuclein to the substantia nigra, followed by daily AZD1390 treatment for six weeks. In AZD1390-treated α-synuclein mice, we observed a significant reduction in the protein level of γ-H2AX, a DDSB marker, along with downregulation of senescence-associated markers, such as p53, Cdkn1a, and NF-κB, suggesting improved genomic integrity and attenuation of cellular senescence, indicating enhanced genomic stability and reduced cellular aging. AZD1390 also significantly dampened neuroinflammatory responses, evidenced by decreased expression of key pro-inflammatory cytokines and chemokines. Interestingly, mice treated with AZD1390 showed significant improvements in behavioral asymmetry and motor deficits, indicating functional recovery. Overall, these results suggest that targeting the DDR via ATM inhibition reduces genotoxic stress, suppresses neuroinflammation, and improves behavioral outcomes in a mouse model of α-synucleinopathy. These findings underscore the therapeutic potential of DDR modulation in PD and related synucleinopathy. Full article

Parkinson’s disease and related synucleinopathies, including dementia with Lewy bodies and multiple system atrophy, are characterised by the pathological aggregation of the α-synuclein (aSyn) protein in neuronal and glial cells, leading to cellular dysfunction and neurodegeneration. This review synthesizes knowledge of aSyn biology, including its structure, aggregation mechanisms, cellular interactions, and systemic influences. We highlight the structural diversity of aSyn aggregates, ranging from oligomers to fibrils, their strain-like properties, and their prion-like propagation. While the role of prion-like mechanisms in disease progression remains a topic of ongoing debate, these processes may contribute to the clinical heterogeneity of synucleinopathies. Dysregulation of protein clearance pathways, including chaperone-mediated autophagy and the ubiquitin–proteasome system, exacerbates aSyn accumulation, while post-translational modifications influence its toxicity and aggregation propensity. Emerging evidence suggests that immune responses and alterations in the gut microbiome are key modulators of aSyn pathology, linking peripheral processes—particularly those of intestinal origin—to central neurodegeneration. Advances in biomarker development, such as cerebrospinal fluid assays, post-translationally modified aSyn, and real-time quaking-induced conversion technology, hold promise for early diagnosis and disease monitoring. Furthermore, positron emission tomography imaging and conformation-specific antibodies offer innovative tools for visualising and targeting aSyn pathology in vivo. Despite significant progress, challenges remain in accurately modelling human synucleinopathies, as existing animal and cellular models capture only specific aspects of the disease. This review underscores the need for more reliable aSyn biomarkers to facilitate the development of effective treatments. Achieving this goal requires an interdisciplinary approach integrating genetic, epigenetic, and environmental insights. Full article

(1) Background: Parkinson’s disease (PD) is a progressive neurodegenerative disorder characterised by dopaminergic neuronal loss. Tissue stem cell-based therapies have emerged as promising candidates for disease modification and symptomatic relief. This scoping review aims to systematically synthesise the literature on tissue stem cell therapies for PD across cellular, animal, and human studies, with a focus on transplantation strategies, mechanisms of action, and therapeutic outcomes. (2) Methods: We identified 1017 records by querying PubMed, Scopus, Cochrane, and the Virtual Health Library. After screening and applying eligibility criteria, 33 experimental studies were included. Data were extracted on study design, tissue stem cell source, type of subject, and therapeutic effects. (3) Results: Most studies (n = 25) involved animal models, with a minority (n = 8) focusing on human applications. Tissue stem cell therapies showed potential to promote dopaminergic differentiation, reduce inflammation and apoptosis, and improve behavioural and motor outcomes. Autologous transplants yielded a higher safety and efficacy compared to allogeneic ones. The beneficial mechanisms of tissue stem cells included neurotrophic support, mitochondrial protection, modulation of the gut–brain axis, and α-synuclein clearance. (4) Conclusions: Tissue stem cell therapies represent a promising approach for PD. However, standardised protocols and long-term safety assessments are essential to optimise their translational potential. Full article

This study investigated the therapeutic potential of the nuclear retinoid X receptor (RXR) in mitigating the progression of alpha-synucleinopathies (αSNPs), particularly in Parkinson’s disease (PD). PD-like pathology in mice was successfully induced through the co-delivery of AAV expressing human α-synuclein (αS) and αS preformed fibrils (PFFs) into the substantia nigra pars compacta (SNpc). Significant increases in Lewy body (LB)-like inclusions, loss of tyrosine hydroxylase-positive (TH+) neurons, and reductions in dopamine (DA) levels in the striatum were observed. Additionally, diminished levels of PPARα and NURR1—proteins essential for neuronal survival—along with elevated expression of IBA1 and GFAP, markers of microglial activation and astrocytic gliosis, respectively, are associated with the pathogenesis of Parkinson’s disease. AAV-mediated overexpression of human RXRα demonstrated preservation of TH+ neurons, prevention of DA decline, and attenuation of αS accumulation. Furthermore, RXR-treated PD brains showed a reduced number of GFAP+ and Iba1+ cells, decreased GFAP+ and IBA1+ immunoreactivity, and fewer and less widespread LB-like aggregates. RXR overexpression also enhanced the production of PPARα and NURR1. These findings suggest that RXRα upregulation promotes neuroprotection by mitigating αSNPs and chronic neuroinflammation, a major contributor to PD progression. This research underscores the therapeutic potential of targeting nuclear receptors, such as RXR, in neurodegenerative diseases like PD. Full article

Hypothermia (HT) is used clinically for neonatal hypoxic–ischemic encephalopathy (HIE); however, the brain protection is incomplete and selective regional vulnerability and lifelong consequences remain. Refractory damage and impairment with HT cooling/rewarming could result from unchecked or altered persisting cell death and proteinopathy. We tested two hypotheses: (1) HT modifies neurodegeneration type, and (2) intrinsically disordered proteins (IDPs) and encephalopathy cause toxic conformer protein (TCP) proteinopathy neonatally. We studied postmortem human neonatal HIE cases with or without therapeutic HT, neonatal piglets subjected to global hypoxia-ischemia (HI) with and without HT or combinations of HI and quinolinic acid (QA) excitotoxicity surviving for 29–96 h to 14 days, and human oligodendrocytes and neurons exposed to QA for cell models. In human and piglet encephalopathies with normothermia, the neuropathology by hematoxylin and eosin staining was similar; necrotic cell degeneration predominated. With HT, neurodegeneration morphology shifted to apoptosis-necrosis hybrid and apoptotic forms in human HIE, while neurons in HI piglets were unshifting and protected robustly. Oligomers and putative TCPs of α-synuclein (αSyn), nitrated-Syn and aggregated αSyn, misfolded/oxidized superoxide dismutase-1 (SOD1), and prion protein (PrP) were detected with highly specific antibodies by immunohistochemistry, immunofluorescence, and immunoblotting. αSyn and SOD1 TCPs were seen in human HIE brains regardless of HT treatment. αSyn and SOD1 TCPs were detected as early as 29 h after injury in piglets and QA-injured human oligodendrocytes and neurons in culture. Cell immunophenotyping by immunofluorescence showed αSyn detected with antibodies to aggregated/oligomerized protein; nitrated-Syn accumulated in neurons, sometimes appearing as focal dendritic aggregations. Co-localization also showed aberrant αSyn accumulating in presynaptic terminals. Proteinase K-resistant PrP accumulated in ischemic Purkinje cells, and their target regions had PrP-positive neuritic plaque-like pathology. Immunofluorescence revealed misfolded/oxidized SOD1 in neurons, axons, astrocytes, and oligodendrocytes. HT attenuated TCP formation in piglets. We conclude that HT differentially affects brain damage in humans and piglets. HT shifts neuronal cell death to other forms in human while blocking ischemic necrosis in piglet for sustained protection. HI and excitotoxicity also acutely induce formation of TCPs and prion-like proteins from IDPs globally throughout the brain in gray matter and white matter. HT attenuates proteinopathy in piglets but seemingly not in humans. Shifting of cell death type and aberrant toxic protein formation could explain the selective system vulnerability, connectome spreading, and persistent damage seen in neonatal HIE leading to lifelong consequences even after HT treatment. Full article

The assembly of amyloidogenic proteins and peptides into toxic oligomeric and fibrillar aggregates is closely connected to the onset and progression of more than 50 protein diseases, such as Alzheimer’s disease, Parkinson’s disease, prion disease, and type 2 diabetes, to name only a few. Considerable research efforts at identifying the therapeutic strategies against these maladies are currently focused on preventing and inhibiting pathogenic protein aggregation by various agents. Plant-based extracts and compounds have emerged as promising sources of potential inhibitors due to their dual role as nutraceuticals as part of healthy diets and as specific pharmaceuticals when administered at higher concentrations. In recent decades, several plant extracts and plant-extracted compounds have shown potential to modulate protein aggregation. An ever-growing body of research on plant-based amyloid inhibitors requires a detail analysis of existing data to identify potential knowledge gaps. This review summarizes the recent progress in amyloid inhibition using 17 flavonoids, 11 polyphenolic non-flavonoid compounds, 23 non-phenolic inhibitors, and 59 plant extracts, with the main emphasis on directly modulating the fibrillation of four amyloid proteins, namely amyloid-β peptide, microtubule-associated protein tau, α-synuclein, and human islet amyloid polypeptide. Full article

Biofilm-associated amyloid proteins have emerged as significant contributors to the progression of neurodegenerative diseases, representing a complex intersection of microorganisms and human health. The cross-beta sheet structure characteristic of amyloids produced by gut-colonizing bacteria remains intact, crucial for the resilience of biofilms. These amyloids exacerbate neurodegenerative disorders such as Alzheimer’s and Parkinson’s by cross-seeding human amyloidogenic proteins like amyloid-beta and α-synuclein, accelerating their misfolding and aggregation. Despite molecular chaperones and heat shock proteins maintaining protein homeostasis, bacterial amyloids can overwhelm them, worsening neuronal damage. Genetic variations in chaperone genes further influence amyloidogenesis and neurodegeneration. Persistent bacterial infections and inflammation compromise the blood-brain barrier, allowing inflammatory molecules and amyloids to enter the brain, perpetuating the cycle of neurodegeneration. The gut-brain axis underscores the impact of dysbiosis and gut microbiota on brain function, potentially contributing to neurodegeneration. The enhancement of biofilm resilience and antibiotic resistance by functional amyloid fibrils complicates the treatment landscape. The interplay among chaperone systems, microbial amyloids, and neurodegenerative diseases underscores the urgent need for advanced treatment strategies targeting these pathways to attenuate disease progression. Understanding the processes that relate biofilm-associated amyloids to the onset of neurological disorders is critical for diagnosing and developing novel treatment strategies. Full article

Neurodegenerative diseases comprise a group of chronic, usually age-related, disorders characterized by progressive neuronal loss, deformation of neuronal structure, or loss of neuronal function, leading to a substantially reduced quality of life. They remain a significant focus of scientific and clinical interest due to their increasing medical and social importance. Most neurodegenerative diseases present intracellular protein aggregation or their extracellular deposition (plaques), such as α-synuclein in Parkinson’s disease and amyloid beta (Aβ)/tau aggregates in Alzheimer’s. Conventional treatments for neurodegenerative conditions incur high costs and are related to the development of several adverse effects. In addition, many patients are irresponsive to them. For these reasons, there is a growing tendency to find new therapeutic approaches to help patients. This review intends to investigate some phytocompounds’ effects on neurodegenerative diseases. These conditions are generally related to increased oxidative stress and inflammation, so phytocompounds can help prevent or treat neurodegenerative diseases. To achieve our aim to provide a critical assessment of the current literature about phytochemicals targeting neurodegeneration, we reviewed reputable databases, including PubMed, EMBASE, and COCHRANE, seeking clinical trials that utilized phytochemicals against neurodegenerative conditions. A few clinical trials investigated the effects of phytocompounds in humans, and after screening, 13 clinical trials were ultimately included following PRISMA guidelines. These compounds include polyphenols (flavonoids such as luteolin and quercetin, phenolic acids such as rosmarinic acid, ferulic acid, and caffeic acid, and other polyphenols like resveratrol), alkaloids (such as berberine, huperzine A, and caffeine), and terpenoids (such as ginkgolides and limonene). The gathered evidence underscores that quercetin, caffeine, ginkgolides, and other phytochemicals are primarily anti-inflammatory, antioxidant, and neuroprotective, counteracting neuroinflammation, neuronal oxidation, and synaptic dysfunctions, which are crucial aspects of neurodegenerative disease intervention in various included conditions, such as Alzheimer’s and other dementias, depression, and neuropsychiatric disorders. In summary, they show that the use of these compounds is related to significant improvements in cognition, memory, disinhibition, irritability/lability, aberrant behavior, hallucinations, and mood disorders. Full article