α-Synuclein-mediated neurodegeneration in Dementia with Lewy bodies: the pathobiology of a paradox

Exploring the Interaction of Human α-Synuclein with Polyethylene Nanoplastics: Insights from Computational Modeling and Experimental Corroboration

Plastics, particularly microplastics (MPs) and nanoplastics (NP), have become major environmental and health concerns due to their high chemical stability. The highly hydrophobic plastics enter living organisms through reversible interactions with biomolecules, forming biocoronas. Following recent reports on plastics breaching the blood-brain barrier, the binding behavior of human α-synuclein (hαSn) with polyethylene-based (PE) plastics was evaluated by using molecular dynamics simulations and experimental methods. The results provided three important findings: (i) hαSn transitions from an open helical to a compact conformation, enhancing intramolecular interactions, (ii) nonoxidized PE NPs (NPnonox) rapidly adsorb hαSn, as supported by experimental data from dynamic light scattering and adsorption isotherms, altering its structure, and (iii) the oxidized NP (NPox) failed to capture hαSn. These interactions were dominated by the N-terminal domain of hαSn, with major contributions from hydrophobic amino acids. These findings raise concerns about the potential pharmacological effects of NP-protein interactions on human health.

Modeling Lewy body disease with SNCA triplication iPSC-derived cortical organoids and identifying therapeutic drugs

Aggregated α-synuclein (α-SYN) proteins, encoded by the SNCA gene, are hallmarks of Lewy body disease (LBD), affecting multiple brain regions. However, the specific mechanisms underlying α-SYN pathology in cortical neurons, crucial for LBD-associated dementia, remain unclear. Here, we recapitulated α-SYN pathologies in human induced pluripotent stem cells (iPSCs)-derived cortical organoids generated from patients with LBD with SNCA gene triplication. Single-cell RNA sequencing, combined with functional and molecular validation, identified synaptic and mitochondrial dysfunction in excitatory neurons exhibiting high expression of the SNCA gene, aligning with observations in the cortex of autopsy-confirmed LBD human brains. Furthermore, we screened 1280 Food and Drug Administration-approved drugs and identified four candidates (entacapone, tolcapone, phenazopyridine hydrochloride, and zalcitabine) that inhibited α-SYN seeding activity in real-time quaking-induced conversion assays with human brains, reduced α-SYN aggregation, and alleviated mitochondrial dysfunction in SNCA triplication organoids and excitatory neurons. Our findings establish human cortical LBD models and suggest potential therapeutic drugs targeting α-SYN aggregation for LBD.

EEG Functional Connectivity Differences Predict Future Conversion to Dementia in Mild Cognitive Impairment With Lewy Body or Alzheimer Disease

BACKGROUND

Predicting which individuals may convert to dementia from mild cognitive impairment (MCI) remains difficult in clinical practice. Electroencephalography (EEG) is a widely available investigation but there is limited research exploring EEG connectivity differences in patients with MCI who convert to dementia.

METHODS

Participants with a diagnosis of MCI due to Alzheimer's disease (MCI-AD) or Lewy body disease (MCI-LB) underwent resting state EEG recording. They were followed up annually with a review of the clinical diagnosis (n = 66). Participants with a diagnosis of dementia at year 1 or year 2 follow up were classed as converters (n = 23) and those with a diagnosis of MCI at year 2 were classed as stable (n = 43). We used phase lag index (PLI) to estimate functional connectivity as well as analysing dominant frequency (DF) and relative band power. The Network-based statistic (NBS) toolbox was used to assess differences in network topology.

RESULTS

The converting group had reduced DF (U = 285.5, p = 0.005) and increased relative pre-alpha power (U = 702, p = 0.005) consistent with previous findings. PLI showed reduced average beta band synchrony in the converting group (U = 311, p = 0.014) as well as significant differences in alpha and beta network topology. Logistic regression models using regional beta PLI values revealed that right central to right lateral (Sens = 56.5%, Spec = 86.0%, -2LL = 72.48, p = 0.017) and left central to right lateral (Sens = 47.8%, Spec = 81.4%, -2LL = 71.37, p = 0.012) had the best classification accuracy and fit when adjusted for age and MMSE score.

CONCLUSION

Patients with MCI who convert to dementia have significant differences in EEG frequency, average connectivity and network topology prior to the onset of dementia. The MCI group is clinically heterogeneous and have underlying physiological differences that may be driving the progression of cognitive symptoms. EEG connectivity could be useful to predict which patients with MCI-AD and MCI-LB convert to dementia, regardless of the neurodegenerative aetiology.

Unlocking the Potential: Semaglutide's Impact on Alzheimer's and Parkinson's Disease in Animal Models

Semaglutide (SEM), a glucagon-like peptide-1 receptor agonist, has garnered increasing interest for its potential therapeutic effects in neurodegenerative disorders such as Alzheimer's disease (AD) and Parkinson's disease (PD). This review provides a comprehensive description of SEM's mechanism of action and its effects in preclinical studies of these debilitating conditions. In animal models of AD, SEM has proved beneficial effects on multiple pathological hallmarks of the disease. SEM administration has been associated with reductions in amyloid-beta plaque deposition and mitigation of neuroinflammation. Moreover, SEM treatment has been shown to ameliorate behavioral deficits related to anxiety and social interaction. SEM-treated animals exhibit improvements in spatial learning and memory retention tasks, as evidenced by enhanced performance in maze navigation tests and novel object recognition assays. Similarly, in animal models of PD, SEM has demonstrated promising neuroprotective effects through various mechanisms. These include modulation of neuroinflammation, enhancement of mitochondrial function, and promotion of neurogenesis. Additionally, SEM has been shown to improve motor function and ameliorate dopaminergic neuronal loss, offering the potential for disease-modifying treatment strategies. Overall, the accumulating evidence from preclinical studies suggests that SEM holds promise as a novel therapeutic approach for AD and PD. Further research is warranted to elucidate the underlying mechanisms of SEM's neuroprotective effects and to translate these findings into clinical applications for the treatment of these devastating neurodegenerative disorders.

Dementia with Lewy bodies: Primary care PAs can make this difficult diagnosis

ABSTRACT

Lewy body dementia is an umbrella term for dementia with Lewy bodies (DLB) and Parkinson disease dementia. These progressive, degenerative brain disorders link dementia with psychosis and parkinsonism and are difficult to diagnose. The diagnosis of DLB is challenging, especially in its early phase, because the presentation is variable. Relevant screening tools and a complete physical examination are essential. Making the correct diagnosis lets patients and caregivers make arrangements, have more timely access to services, improve patient quality of life, and lessen the burden on caregivers.

Research progress of PROTACs for neurodegenerative diseases therapy

Neurodegenerative diseases (NDD) are characterized by the gradual deterioration of neuronal function and integrity, resulting in an overall decline in brain function. The existing therapeutic options for NDD, including Alzheimer's disease, Parkinson's disease, and Huntington's disease, fall short of meeting the clinical demand. A prominent pathological hallmark observed in numerous neurodegenerative disorders is the aggregation and misfolding of proteins both within and outside neurons. These abnormal proteins play a pivotal role in the pathogenesis of neurodegenerative diseases. Targeted degradation of irregular proteins offers a promising avenue for NDD treatment. Proteolysis-targeting chimeras (PROTACs) function via the ubiquitin-proteasome system and have emerged as a novel and efficacious approach in drug discovery. PROTACs can catalytically degrade "undruggable" proteins even at exceptionally low concentrations, allowing for precise quantitative control of aberrant protein levels. In this review, we present a compilation of reported PROTAC structures and their corresponding biological activities aimed at addressing NDD. Spanning from 2016 to present, this review provides an up-to-date overview of PROTAC-based therapeutic interventions. Currently, most protein degraders intended for NDD treatment remain in the preclinical research phase. Overcoming several challenges is imperative, including enhancing oral bioavailability and permeability across the blood-brain barrier, before these compounds can progress to clinical research or eventually reach the market. However, armed with an enhanced comprehension of the underlying pathological mechanisms and the emergence of innovative scaffolds for protein degraders, along with further structural optimization, we are confident that PROTAC possesses the potential to make substantial breakthroughs in the field of neurodegenerative diseases.

Grey matter networks in women and men with dementia with Lewy bodies

Sex differences permeate many aspects of dementia with Lewy bodies (DLB), yet sex differences in patterns of neurodegeneration in DLB remain largely unexplored. Here, we test whether grey matter networks differ between sexes in DLB and compare these findings to sex differences in healthy controls. In this cross-sectional study, we analysed clinical and neuroimaging data of patients with DLB and cognitively healthy controls matched for age and sex. Grey matter networks were constructed by pairwise correlations between 58 regional volumes after correction for age, intracranial volume, and centre. Network properties were compared between sexes and diagnostic groups. Additional analyses were conducted on w-scored data to identify DLB-specific sex differences. Data from 119 (68.7 ± 8.4 years) men and 45 women (69.9 ± 9.1 years) with DLB, and 164 healthy controls were included in this study. Networks of men had a lower nodal strength compared to women. In comparison to healthy women, the grey matter networks of healthy men showed a higher global efficiency, modularity, and fewer modules. None of the network measures showed significant sex differences in DLB. Comparing DLB patients with healthy controls revealed global differences in women and more local differences in men. Modular analyses showed a more distinct demarcation between cortical and subcortical regions in men compared with women. While topologies of grey matter networks differed between sexes in healthy controls, those sex differences were diluted in DLB patients. These findings suggest a disease-driven convergence of neurodegenerative patterns in women and men with DLB, which may inform precision medicine in DLB.

Toward Personalized Medicine Approaches for Parkinson Disease Using Digital Technologies

Parkinson disease (PD) is a complex neurodegenerative disorder that afflicts over 10 million people worldwide, resulting in debilitating motor and cognitive impairment. In the United States alone (with approximately 1 million cases), the economic burden for treating and caring for persons with PD exceeds US $50 billion and myriad therapeutic approaches are under development, including both symptomatic- and disease-modifying agents. The challenges presented in addressing PD are compounded by observations that numerous, statistically distinct patient phenotypes present with a wide variety of motor and nonmotor symptomatic profiles, varying responses to current standard-of-care symptom-alleviating medications (L-DOPA and dopaminergic agonists), and different disease trajectories. The existence of these differing phenotypes highlights the opportunities in personalized approaches to symptom management and disease control. The prodromal period of PD can span across several decades, allowing the potential to leverage the unique array of composite symptoms presented to trigger early interventions. This may be especially beneficial as disease progression in PD (alongside Alzheimer disease and Huntington disease) may be influenced by biological processes such as oxidative stress, offering the potential for individual lifestyle factors to be tailored to delay disease onset. In this viewpoint, we offer potential scenarios where emerging diagnostic and monitoring strategies might be tailored to the individual patient under the tenets of P4 medicine (predict, prevent, personalize, and participate). These approaches may be especially relevant as the causative factors and biochemical pathways responsible for the observed neurodegeneration in patients with PD remain areas of fluid debate. The numerous observational patient cohorts established globally offer an excellent opportunity to test and refine approaches to detect, characterize, control, modify the course, and ultimately stop progression of this debilitating disease. Such approaches may also help development of parallel interventive strategies in other diseases such as Alzheimer disease and Huntington disease, which share common traits and etiologies with PD. In this overview, we highlight near-term opportunities to apply P4 medicine principles for patients with PD and introduce the concept of composite orthogonal patient monitoring.

Alpha synuclein post translational modifications: potential targets for Parkinson's disease therapy?

Parkinson's disease (PD) is the most common neurodegenerative disorder with motor symptoms. The neuropathological alterations characterizing the brain of patients with PD include the loss of dopaminergic neurons of the nigrostriatal system and the presence of Lewy bodies (LB), intraneuronal inclusions that are mainly composed of alpha-synuclein (α-Syn) fibrils. The accumulation of α-Syn in insoluble aggregates is a main neuropathological feature in PD and in other neurodegenerative diseases, including LB dementia (LBD) and multiple system atrophy (MSA), which are therefore defined as synucleinopathies. Compelling evidence supports that α-Syn post translational modifications (PTMs) such as phosphorylation, nitration, acetylation, O-GlcNAcylation, glycation, SUMOylation, ubiquitination and C-terminal cleavage, play important roles in the modulation α-Syn aggregation, solubility, turnover and membrane binding. In particular, PTMs can impact on α-Syn conformational state, thus supporting that their modulation can in turn affect α-Syn aggregation and its ability to seed further soluble α-Syn fibrillation. This review focuses on the importance of α-Syn PTMs in PD pathophysiology but also aims at highlighting their general relevance as possible biomarkers and, more importantly, as innovative therapeutic targets for synucleinopathies. In addition, we call attention to the multiple challenges that we still need to face to enable the development of novel therapeutic approaches modulating α-Syn PTMs.

Kisspeptin-10 Mitigates α-Synuclein-Mediated Mitochondrial Apoptosis in SH-SY5Y-Derived Neurons via a Kisspeptin Receptor-Independent Manner

The hypothalamic neurohormone kisspeptin-10 (KP-10) was inherently implicated in cholinergic pathologies when aberrant fluctuations of expression patterns and receptor densities were discerned in neurodegenerative micromilieus. That said, despite variable degrees of functional redundancy, KP-10, which is biologically governed by its cognate G-protein-coupled receptor, GPR54, attenuated the progressive demise of α-synuclein (α-syn)-rich cholinergic-like neurons. Under explicitly modeled environments, in silico algorithms further rationalized the surface complementarities between KP-10 and α-syn when KP-10 was unambiguously accommodated in the C-terminal binding pockets of α-syn. Indeed, the neuroprotective relevance of KP-10's binding mechanisms can be insinuated in the amelioration of α-syn-mediated neurotoxicity; yet it is obscure whether these extenuative circumstances are contingent upon prior GPR54 activation. Herein, choline acetyltransferase (ChAT)-positive SH-SY5Y neurons were engineered ad hoc to transiently overexpress human wild-type or E46K mutant α-syn while the mitigation of α-syn-induced neuronal death was ascertained via flow cytometric and immunocytochemical quantification. Recapitulating the specificity observed on cell viability, exogenously administered KP-10 (0.1 µM) substantially suppressed wild-type and E46K mutant α-syn-mediated apoptosis and mitochondrial depolarization in cholinergic differentiated neurons. In particular, co-administrations with a GPR54 antagonist, kisspeptin-234 (KP-234), failed to abrogate the robust neuroprotection elicited by KP-10, thereby signifying a GPR54 dispensable mechanism of action. Consistent with these observations, KP-10 treatment further diminished α-syn and ChAT immunoreactivity in neurons overexpressing wild-type and E46K mutant α-syn. Overall, these findings lend additional credence to the previous notion that KP-10's binding zone may harness efficacious moieties of neuroprotective intent.

Sex differences in grey matter networks in dementia with Lewy bodies

Objectives

Sex differences permeate many aspects of dementia with Lewy bodies (DLB), including epidemiology, pathogenesis, disease progression, and symptom manifestation. However, less is known about potential sex differences in patterns of neurodegeneration in DLB. Here, we test whether grey matter networks also differ between female and male DLB patients. To assess the specificity of these sex differences to DLB, we additionally investigate sex differences in healthy controls (HCs).

Methods

A total of 119 (68.7 ± 8.4 years) male and 45 female (69.9 ± 9.1 years) DLB patients from three European centres and the Mayo Clinic were included in this study. Additionally, we included 119 male and 45 female age-matched HCs from the Mayo Clinic. Grey matter volumes of 58 cortical, subcortical, cerebellar, and pontine brain regions derived from structural magnetic resonance images were corrected for age, intracranial volume, and centre. Sex-specific grey matter networks for DLB patients and HCs were constructed by correlating each pair of brain regions. Network properties of the correlation matrices were compared between sexes and groups. Additional analyses were conducted on W-scored data to identify DLB-specific findings.

Results

Networks of male HCs and male DLB patients were characterised by a lower nodal strength compared to their respective female counterparts. In comparison to female HCs, the grey matter networks of male HCs showed a higher global efficiency, modularity, and a lower number of modules. None of the global and nodal network measures showed significant sex differences in DLB.

Conclusions

The disappearance of sex differences in the structural grey matter networks of DLB patients compared to HCs may indicate a sex-dependent network vulnerability to the alpha-synuclein pathology in DLB. Future studies might investigate whether the differences in structural network measures are associated with differences in cognitive scores and clinical symptoms between the sexes.

Kisspeptin-10 Rescues Cholinergic Differentiated SHSY-5Y Cells from α-Synuclein-Induced Toxicity In Vitro

The neuropathological substrate of dementia with Lewy bodies (DLB) is defined by the inextricable cross-seeding accretion of amyloid-β (Aβ) and α-synuclein (α-syn)-laden deposits in cholinergic neurons. The recent revelation that neuropeptide kisspeptin-10 (KP-10) is able to mitigate Aβ toxicity via an extracellular binding mechanism may provide a new horizon for innovative drug design endeavors. Considering the sequence similarities between α-syn’s non-amyloid-β component (NAC) and Aβ’s C-terminus, we hypothesized that KP-10 would enhance cholinergic neuronal resistance against α-syn’s deleterious consequences through preferential binding. Here, human cholinergic SH-SY5Y cells were transiently transformed to upsurge the mRNA expression of α-syn while α-syn-mediated cholinergic toxicity was quantified utilizing a standardized viability-based assay. Remarkably, the E46K mutant α-syn displayed elevated α-syn mRNA levels, which subsequently induced more cellular toxicity compared with the wild-type α-syn in choline acetyltransferase (ChAT)-positive cholinergic neurons. Treatment with a high concentration of KP-10 (10 µM) further decreased cholinergic cell viability, while low concentrations of KP-10 (0.01–1 µM) substantially suppressed wild-type and E46K mutant α-syn-mediated toxicity. Correlating with the in vitro observations are approximations from in silico algorithms, which inferred that KP-10 binds favorably to the C-terminal residues of wild-type and E46K mutant α-syn with CDOCKER energy scores of −118.049 kcal/mol and −114.869 kcal/mol, respectively. Over the course of 50 ns simulation time, explicit-solvent molecular dynamics conjointly revealed that the docked complexes were relatively stable despite small-scale fluctuations upon assembly. Taken together, our findings insinuate that KP-10 may serve as a novel therapeutic scaffold with far-reaching implications for the conceptualization of α-syn-based treatments.

In Pancreatic Adenocarcinoma Alpha-Synuclein Increases and Marks Peri-Neural Infiltration

α-Synuclein (α-syn) is a protein involved in neuronal degeneration. However, the family of synucleins has recently been demonstrated to be involved in the mechanisms of oncogenesis by selectively accelerating cellular processes leading to cancer. Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal human cancers, with a specifically high neurotropism. The molecular bases of this biological behavior are currently poorly understood. Here, α-synuclein was analyzed concerning the protein expression in PDAC and the potential association with PDAC neurotropism. Tumor (PDAC) and extra-tumor (extra-PDAC) samples from 20 patients affected by PDAC following pancreatic resections were collected at the General Surgery Unit, University of Pisa. All patients were affected by moderately or poorly differentiated PDAC. The amount of α-syn was compared between tumor and extra-tumor specimen (sampled from non-affected neighboring pancreatic areas) by using in situ immuno-staining with peroxidase anti-α-syn immunohistochemistry, α-syn detection by using Western blotting, and electron microscopy by using α-syn-conjugated immuno-gold particles. All the methods consistently indicate that each PDAC sample possesses a higher amount of α-syn compared with extra-PDAC tissue. Moreover, the expression of α-syn was much higher in those PDAC samples from tumors with perineural infiltration compared with tumors without perineural infiltration.