Self-propagation of pathogenic protein aggregates in neurodegenerative diseases

The growth rate of senile plaques is determined by the competition between the rate of deposition of free Aβ aggregates into plaques and the autocatalytic production of free Aβ aggregates

The formation of amyloid beta (Aβ) deposits (senile plaques) is one of the hallmarks of Alzheimer's disease (AD). This study investigates what processes are primarily responsible for their formation. A model is developed to simulate the diffusion of amyloid beta (Aβ) monomers, the production of free Aβ aggregates through nucleation and autocatalytic processes, and the deposition of these aggregates into senile plaques. The model suggests that efficient degradation of Aβ monomers alone may suffice to prevent the growth of senile plaques, even without degrading Aβ aggregates and existing plaques. This is because the degradation of Aβ monomers interrupts the supply of reactants needed for plaque formation. The impact of Aβ monomer diffusivity is demonstrated to be small, enabling the application of the lumped capacitance approximation and the derivation of approximate analytical solutions for limiting cases with both small and large rates of Aβ aggregate deposition into plaques. It is found that the rate of plaque growth is governed by two competing processes. One is the deposition rate of free Aβ aggregates into senile plaques. If this rate is small, the plaque grows slowly. However, if the rate of deposition of Aβ aggregates into senile plaques is very large, the free Aβ aggregates are removed from the intracellular fluid by deposition into the plaques, leaving insufficient free Aβ aggregates to catalyze the production of new aggregates. This suggests that under certain conditions, Aβ plaques may offer neuroprotection and impede their own growth. Additionally, it indicates that there exists an optimal rate of deposition of free Aβ aggregates into the plaques, at which the plaques attain their maximum size.

Frontiers of Neurodegenerative Disease Treatment: Targeting Immune Cells in Brain Border Regions

Neurodegenerative diseases (NDs) demonstrate a complex interaction with the immune system, challenging the traditional view of the brain as an "immune-privileged" organ. Microglia were once considered the sole guardians of the brain's immune response. However, recent research has revealed the critical role of peripheral immune cells located in key brain regions like the meninges, choroid plexus, and perivascular spaces. These previously overlooked cells are now recognized as contributors to the development and progression of NDs. This newfound understanding opens doors for pioneering therapeutic strategies. By targeting these peripheral immune cells, we may be able to modulate the brain's immune environment, offering an alternative approach to treat NDs and circumvent the challenges posed by the blood-brain barrier. This comprehensive review will scrutinize the latest findings on the complex interactions between these peripheral immune cells and NDs. It will also critically assess the prospects of targeting these cells as a ground-breaking therapeutic avenue for these debilitating disorders.

Unveiling the veil of RNA binding protein phase separation in cancer biology and therapy

RNA-binding protein (RBP) phase separation in oncology reveals a complex interplay crucial for understanding tumor biology and developing novel therapeutic strategies. Aberrant phase separation of RBPs significantly influences gene regulation, signal transduction, and metabolic reprogramming, contributing to tumorigenesis and drug resistance. Our review highlights the integral roles of RBP phase separation in stress granule dynamics, mRNA stabilization, and the modulation of transcriptional and translational processes. Furthermore, interactions between RBPs and non-coding RNAs add a layer of complexity, providing new insights into their collaborative roles in cancer progression. The intricate relationship between RBPs and phase separation poses significant challenges but also opens up novel opportunities for targeted therapeutic interventions. Advancing our understanding of the molecular mechanisms and regulatory networks governing RBP phase separation could lead to breakthroughs in cancer treatment strategies.

Induction of tau pathology and motor dysfunction in mice by urinary exosomes from progressive supranuclear palsy patients

BACKGROUND

Progressive supranuclear palsy (PSP) is characterized by the presence of hyperphosphorylated and misfolded tau aggregates in neurons and glia. Recent studies have illuminated the prion-like cell-to-cell propagation of tau via exosomes. Recognizing the potential significance of excretion through urine as a crucial pathway for eliminating pathological tau from the central nervous system, this study aimed to investigate whether exosomes derived from the urine of PSP-Richardson's syndrome (PSP-RS) patients can elicit tau pathology and PSP-like symptoms in mice.

METHODS

Urinary exosomes obtained from PSP-RS patients and normal controls (NCs) were stereotactically injected into the bilateral globus pallidus of mouse brains. Behavioral analyses were conducted every 3 months post-injection. After 6 months, mice were sacrificed for pathological evaluation.

RESULTS

Elevated levels of phosphorylated tau and neural cell markers were observed in urinary exosomes from PSP-RS patients compared to NCs. At the 6-month mark post-injection, tau inclusions were evident in the brains of mice receiving urinary exosomes from PSP-RS patients, with widespread distribution in both injection sites and distant brain regions (cortex, hippocampus, and substantia nigra). Tau pathology manifested in neurons and astrocytes. Moreover, mice injected with urinary exosomes from PSP-RS patients exhibited impaired motor coordination and balance, mirroring PSP motor symptoms.

CONCLUSION

Our findings indicate that urinary exosomes from PSP-RS patients can induce tau pathology and trigger PSP-like motor symptoms in mice. This leads to the hypothesis that exosomes may play a role in the pathogenesis of PSP.

Traumatic Brain Injury in Mice Generates Early-Stage Alzheimer's Disease Related Protein Pathology that Correlates with Neurobehavioral Deficits

Traumatic brain injury (TBI) increases the long-term risk of neurodegenerative diseases, including Alzheimer's disease (AD). Here, we demonstrate that protein variant pathology generated in brain tissue of an experimental TBI mouse model is similar to protein variant pathology observed during early stages of AD, and that subacute accumulation of AD associated variants of amyloid beta (Aβ) and tau in the TBI mouse model correlated with behavioral deficits. Male C57BL/6 mice were subjected to midline fluid percussion injury or to sham injury, after which sensorimotor function (rotarod, neurological severity score), cognitive deficit (novel object recognition), and affective deficits (elevated plus maze, forced swim task) were assessed post-injury (DPI). Protein pathology at 7, 14, and 28 DPI was measured in multiple brain regions using an immunostain panel of reagents selectively targeting different neurodegenerative disease-related variants of Aβ, tau, TDP-43, and alpha-synuclein. Overall, TBI resulted in sensorimotor deficits and accumulation of AD-related protein variant pathology near the impact site, both of which returned to sham levels by 14 DPI. Individual mice, however, showed persistent behavioral deficits and/or accumulation of toxic protein variants at 28 DPI. Behavioral outcomes of each mouse were correlated with levels of seven different protein variants in ten brain regions at specific DPI. Out of 21 significant correlations between protein variant levels and behavioral deficits, 18 were with variants of Aβ or tau. Correlations at 28 DPI were all between a single Aβ or tau variant, both of which are strongly associated with human AD cases. These data provide a direct mechanistic link between protein pathology resulting from TBI and the hallmarks of AD.

Thy1-ApoE4/C/EBPβ double transgenic mice act as a sporadic model with Alzheimer's disease

Early onset familial Alzheimer's disease (FAD) with APP, PS1/2 (presenilins) mutation accounts for only a small portion of AD cases, and most are late-onset sporadic. However, majority of AD mouse models are developed to mimic the genetic cause of human AD by overexpressing mutated forms of human APP, PS1/2, and/or Tau protein, though there is no Tau mutation in AD, and no single mouse model recapitulates all aspects of AD pathology. Here, we report Thy1-ApoE4/C/EBPβ double transgenic mouse model that demonstrates key AD pathologies in an age-dependent manner in absence of any human APP or PS1/2 mutation. Using the clinical diagnosis criteria, we show that this mouse model exhibits tempo-spatial features in AD patient brains, including progressive cognitive decline associated with brain atrophy, which is accompanied with extensive neuronal degeneration. Remarkably, the mice display gradual Aβ aggregation and neurofibrillary tangles formation in the brain validated by Aβ PET and Tau PET. Moreover, the mice reveal widespread neuroinflammation as shown in AD brains. Hence, Thy1-ApoE4/C/EBPβ mouse model acts as a sporadic AD mouse model, reconstituting the major AD pathologies.

Insight into the binding mechanisms of fluorinated 2-aminothiazole sulfonamide and human serum albumin: Spectroscopic and in silico approaches

4-Fluoro-N-(thiazol-2-yl)benzenesulfonamide (3) is a novel fluorinated compound, containing various biological activities. Therefore, absorption spectroscopy, fluorescence quenching, molecular docking, and molecular simulation were employed to investigate the interaction between 3 and human serum albumin (HSA). Firstly, compound 3 meets all criteria for drug-likeness prediction. UV absorption spectra revealed the interaction of 3 with HSA altered the microenvironment of protein, as well as circular dichroism spectroscopic analysis indicated slightly conformational changes and a reduction in α-helical content. The binding parameters of the HSA-3 complex suggested that fluorescence quenching is driven by combined static and dynamic processes. Additionally, the stability of the complex is attributed to conventional hydrogen and hydrophobic bonding interactions. Furthermore, esterase-like activity indicated that the binding of 3 might disrupt HSA's bond networks, leading to structural alterations. Consequently, the strong binding constant (Ka ≈ 1.204 × 106 M-1) aligns with the predicted unbound fraction (0.28) in serum, indicating that thiazole 3 has good bioavailability in plasma and can be effectively transported to target sites, thereby exerting its pharmaceutical effects. However, careful dosage management is essential to prevent potential adverse effects. Overall, these findings highlight the potential of 3 as a therapeutic agent, emphasizing the need for further research to optimize its uses.

Rapid and sensitive determination of residual prion infectivity from prion-decontaminated surfaces

Prion diseases are untreatable fatal transmissible neurodegenerative diseases that affect a wide range of mammals, including humans, and are caused by PrPSc, the infectious self-templating conformation of the host-encoded protein, PrPC. Prion diseases can be transmitted via surfaces (e.g., forceps, EEG electrodes) in laboratory and clinical settings. Here, we use a combination of surface swabbing and real-time quaking-induced conversion (RT-QuIC) to test for residual surface-associated prions following prion disinfection. We found that treatment of several prion-contaminated laboratory and clinically relevant surfaces with either water or 70% EtOH resulted in robust detection of surface-associated prions. In contrast, treatment of surfaces with sodium hypochlorite resulted in a failure to detect surface-associated prions. RT-QuIC analysis of prion-contaminated stainless steel wires paralleled the findings of the surface swab studies. Importantly, animal bioassay and RT-QuIC analysis of the same swab extracts are in agreement. We report on conditions that may interfere with the assay that need to be taken into consideration before using this technique. Overall, this method can be used to survey laboratory and clinical surfaces for prion infectivity following prion decontamination protocols.IMPORTANCEPrion diseases can be accidentally transmitted in clinical and occupational settings. While effective means of prion decontamination exist, methods for determining the effectiveness are only beginning to be described. Here, we analyze surface swab extracts using real-time quaking-induced conversion (RT-QuIC) to test for residual prions following prion disinfection of relevant clinical and laboratory surfaces. We found that this method can rapidly determine the efficacy of surface prion decontamination. Importantly, examination of surface extracts with RT-QuIC and animal bioassay produced similar findings, suggesting that this method can accurately assess the reduction in prion titer. We identified surface contaminants that interfere with the assay, which may be found in clinical and laboratory settings. Overall, this method can enhance clinical and laboratory prion safety measures.

Molecular Therapeutics in Development to Treat Alzheimer's Disease

Until recently, only symptomatic therapies, in the form of acetylcholine esterase inhibitors and NMDA-receptor antagonists, have been available for the treatment of Alzheimer's disease. However, advancements in our understanding of the amyloid cascade hypothesis have led to a development of disease-modifying therapeutic strategies. These include immunotherapies based on an infusion of monoclonal antibodies against amyloid-β, three of which have been approved for the treatment of Alzheimer's disease in the USA (one of them, lecanemab, has also been approved in several other countries). They all lead to a dramatic reduction of amyloid plaques in the brain, whereas their clinical effects have been more limited. Moreover, they can all lead to side effects in the form of amyloid-related imaging abnormalities. Ongoing developments aim at facilitating their administration, further improving their effects and reducing the risk for amyloid-related imaging abnormalities. Moreover, a number of anti-tau immunotherapies are in clinical trials, but none has so far shown any robust effects on symptoms or pathology. Another line of development is represented by gene therapy. To date, only antisense oligonucleotides against amyloid precursor protein/amyloid-β and tau have reached the clinical trial stage but a variety of gene editing strategies, such as clustered regularly interspaced short palindromic repeats/Cas9-mediated non-homologous end joining, base editing, and prime editing, have all shown promise on preclinical disease models. In addition, a number of other pharmacological compounds targeting a multitude of biochemical processes, believed to be centrally involved in Alzheimer's disease, are currently being evaluated in clinical trials. This article delves into current and future perspectives on the treatment of Alzheimer's disease, with an emphasis on immunotherapeutic and gene therapeutic strategies.

The prion principle and Alzheimer's disease

Similarities to molecular mechanisms underlying prion diseases may help to refine Alzheimer's disease therapies.

Temporal control of acute protein aggregate turnover by UBE3C and NRF1-dependent proteasomal pathways

A hallmark of neurodegenerative diseases is the progressive loss of proteostasis, leading to the accumulation of misfolded proteins or protein aggregates, with subsequent cytotoxicity. To combat this toxicity, cells have evolved degradation pathways (ubiquitin-proteasome system and autophagy) that detect and degrade misfolded proteins. However, studying the underlying cellular pathways and mechanisms has remained a challenge, as formation of many types of protein aggregates is asynchronous, with individual cells displaying distinct kinetics, thereby hindering rigorous time-course studies. Here, we merge a kinetically tractable and synchronous agDD-GFP system for aggregate formation with targeted gene knockdowns, to uncover degradation mechanisms used in response to acute aggregate formation. We find that agDD-GFP forms amorphous aggregates by cryo-electron tomography at both early and late stages of aggregate formation. Aggregate turnover occurs in a proteasome-dependent mechanism in a manner that is dictated by cellular aggregate burden, with no evidence of the involvement of autophagy. Lower levels of misfolded agDD-GFP, enriched in oligomers, utilizes UBE3C-dependent proteasomal degradation in a pathway that is independent of RPN13 ubiquitylation by UBE3C. Higher aggregate burden activates the NRF1 transcription factor to increase proteasome subunit transcription, and subsequent degradation capacity of cells. Loss or gain of NRF1 function alters the turnover of agDD-GFP under conditions of high aggregate burden. Together, these results define the role of UBE3C in degradation of this class of misfolded aggregation-prone proteins and reveals a role for NRF1 in proteostasis control in response to widespread protein aggregation.

TDP-43 proteinopathy in frontotemporal lobar degeneration and amyotrophic lateral sclerosis: From pathomechanisms to therapeutic strategies

Proteostasis failure is a common pathological characteristic in neurodegenerative diseases. Revitalizing clearance systems could effectively mitigate these diseases. The transactivation response (TAR) DNA-binding protein 43 (TDP-43) plays a critical role as an RNA/DNA-binding protein in RNA metabolism and synaptic function. Accumulation of TDP-43 aggregates in the central nervous system is a hallmark of frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS). Autophagy, a major and highly conserved degradation pathway, holds the potential for degrading aggregated TDP-43 and alleviating FTLD/ALS. This review explores the causes of TDP-43 aggregation, FTLD/ALS-related genes, key autophagy factors, and autophagy-based therapeutic strategies targeting TDP-43 proteinopathy. Understanding the underlying pathological mechanisms of TDP-43 proteinopathy can facilitate therapeutic interventions.

Proliferation of SH-SY5Y neuroblastoma cells on confined spaces

BACKGROUND

Microfluidics offers precise drug delivery and continuous monitoring of cell functions, which is crucial for studying the effects of toxins and drugs. Ensuring proper cell growth in these space-constrained systems is essential for obtaining consistent results comparable to standard Petri dishes.

NEW METHOD

We investigated the proliferation of SH-SY5Y cells on circular polycarbonate chambers with varying surface areas. SH-SY5Y cells were chosen for their relevance in neurodegenerative disease research.

RESULTS

Our study demonstrates a correlation between the chamber surface area and SH-SY5Y cell growth rates. Cells cultured in chambers larger than 10 mm in diameter exhibited growth comparable to standard 60-mm dishes. In contrast, smaller chambers significantly impeded growth, even at identical seeding densities. Similar patterns were observed for HeLaGFP cells, while 16HBE14σ cells proliferated efficiently regardless of chamber size. Additionally, SH-SY5Y cells were studied in a 12-mm diameter sealed chamber to assess growth under restricted gas exchange conditions.

COMPARISON WITH EXISTING METHODS

Our findings underscore the limitations of small chamber sizes in microfluidic systems for SH-SY5Y cells, an issue not typically addressed by conventional methods.

CONCLUSIONS

SH-SY5Y cell growth is highly sensitive to spatial constraints, with markedly reduced proliferation in chambers smaller than 10 mm. This highlights the need to carefully consider chamber size in microfluidic experiments to achieve cell growth rates comparable to standard culture dishes. The study also shows that while SH-SY5Y and HeLaGFP cells are affected by chamber size, 16HBE14σ cells are not. These insights are vital for designing effective microfluidic systems for bioengineering research.

α-Synuclein strain propagation is independent of cellular prion protein expression in a transgenic synucleinopathy mouse model

The cellular prion protein, PrPC, has been postulated to function as a receptor for α-synuclein, potentially facilitating cell-to-cell spreading and/or toxicity of α-synuclein aggregates in neurodegenerative disorders such as Parkinson's disease. Previously, we generated the "Salt (S)" and "No Salt (NS)" strains of α-synuclein aggregates that cause distinct pathological phenotypes in M83 transgenic mice overexpressing A53T-mutant human α-synuclein. To test the hypothesis that PrPC facilitates the propagation of α-synuclein aggregates, we produced M83 mice that either express or do not express PrPC. Following intracerebral inoculation with the S or NS strain, the absence of PrPC in M83 mice did not prevent disease development and had minimal influence on α-synuclein strain-specified attributes such as the extent of cerebral α-synuclein deposition, selective targeting of specific brain regions and cell types, the morphology of induced α-synuclein deposits, and the structural fingerprints of protease-resistant α-synuclein aggregates. Likewise, there were no appreciable differences in disease manifestation between PrPC-expressing and PrPC-lacking M83 mice following intraperitoneal inoculation of the S strain. Interestingly, intraperitoneal inoculation with the NS strain resulted in two distinct disease phenotypes, indicative of α-synuclein strain evolution, but this was also independent of PrPC expression. Overall, these results suggest that PrPC plays at most a minor role in the propagation, neuroinvasion, and evolution of α-synuclein strains in mice that express A53T-mutant human α-synuclein. Thus, other putative receptors or cell-to-cell propagation mechanisms may have a larger effect on the spread of α-synuclein aggregates during disease.

Presenilin deficiency enhances tau phosphorylation and its secretion

Alzheimer's disease (AD) is characterized by the accumulation of abnormally folded amyloid β-protein (Aβ) in the brain parenchyma and phosphorylated tau in neurons. Presenilin (PS, PSEN) 1 and PS2 are essential components of γ-secretase, which is responsible for the cleavage of amyloid precursor protein (APP) to generate Aβ. PSEN mutations are associated with tau aggregation in frontotemporal dementia, regardless of the presence or absence of Aβ pathology. However, the mechanism by which PS regulates tau aggregation is still unknown. Here, we found that tau phosphorylation and secretion were significantly increased in PS double-knock-out (PS1/2-/-) fibroblasts compared with wild-type fibroblasts. Tau-positive vesicles in the cytoplasm were significantly increased in PS1/2-/- fibroblasts. Active GSK-3β was increased in PS1/2-/- fibroblasts, and inhibiting GSK3β activity in PS1/2-/- fibroblasts resulted in decreased tau phosphorylation and secretion. Transfection of WT human PS1 and PS2 reduced the secretion of phosphorylated tau and active GSK-3β in PS1/2-/- fibroblasts. However, PS1D257A without γ-secretase activity did not decrease the secretion of phosphorylated tau. Furthermore, nicastrin deficiency also increased tau phosphorylation and secretion. These results suggest that deficient PS complex maturation may increase tau phosphorylation and secretion. Thus, our studies discover a new pathway by which PS regulates tau phosphorylation/secretion and pathology independent of Aβ and suggest that PS serves as a potential therapeutic target for treating neurodegenerative diseases involving tau aggregation.

Shared and distinct cortical morphometric alterations in five neuropsychiatric symptoms of Parkinson's disease

Neuropsychiatric symptoms (including anxiety, depression, apathy, impulse-compulsive behaviors and hallucinations) are among the most common non-motor features of Parkinson's disease. Whether these symptoms should be considered as a direct consequence of the pathophysiologic mechanisms of Parkinson's disease is controversial. Morphometric similarity network analysis and epicenter mapping approach were performed on T1-weighted images of 505 patients with Parkinson's disease and 167 age- and sex-matched healthy participants from Parkinson's Progression Markers Initiative database to reveal the commonalities and specificities of distinct neuropsychiatric symptoms. Abnormal cortical co-alteration pattern in patients with neuropsychiatric symptoms was in somatomotor, vision and frontoparietal regions, with epicenters in somatomotor regions. Apathy, impulse-compulsive behaviors and hallucinations shares structural abnormalities in somatomotor and vision regions, with epicenters in somatomotor regions. In contrast, the cortical abnormalities and epicenters of anxiety and depression were prominent in the default mode network regions. By embedding each symptom within their co-alteration space, we observed a cluster composed of apathy, impulse-compulsive behaviors and hallucinations, while anxiety and depression remained separate. Our findings indicate different structural mechanisms underlie the occurrence and progression of different neuropsychiatric symptoms. Based upon these results, we propose that apathy, impulse-compulsive behaviors and hallucinations are directly related to damage of motor circuit, while anxiety and depression may be the combination effects of primary pathophysiology of Parkinson's disease and psychosocial causes.

How fiber bundle alterations differ in presumed LATE and amnestic Alzheimer's disease

INTRODUCTION

Typical Alzheimer's disease (AD) and limbic-predominant age-related TAR DNA-binding protein 43 (TDP-43) encephalopathy (LATE) are two neurodegenerative diseases that present with a similar initial amnestic clinical phenotype but are associated with distinct proteinopathies.

METHODS

We investigated white matter (WM) fiber bundle alterations, using fixel-based analysis, a state-of-the-art diffusion magnetic resonance imaging model, in early AD, presumed LATE, and controls. We also investigated regional cortical atrophy.

RESULTS

Both amnestic AD and presumed LATE patients exhibited WM alterations in tracts of the temporal and limbic lobes and in callosal fibers connecting superior frontal gyri. In addition, presumed LATE patients showed alterations in callosal fibers connecting the middle frontal gyri and in the cerebello-thalamo-cortical tract. Cortical thickness was reduced in regions connected by the most altered tracts.

DISCUSSION

These findings, the first to describe WM fiber bundle alterations in presumed LATE, are consistent with results on cortical atrophy and with the staging system of tau or TDP-43 accumulation.

HIGHLIGHTS

Fixel-based analysis revealed white matter (WM) fiber bundle alterations in presumed limbic-predominant age-related TAR DNA-binding protein 43 encephalopathy (LATE) patients identified by isolated episodic/limbic amnesia, the absence of positive Alzheimer's disease (AD) biomarkers, and no other neurological diagnosis after 2 years of follow-up. Presumed LATE and amnestic AD shared similar patterns of WM alterations in fiber bundles of the limbic and temporal lobes, in congruence with their similar limbic cognitive phenotype. Presumed LATE differed from AD by the alteration of the callosal fibers connecting the middle frontal gyri and of the cerebello-thalamo-cortical tract. WM fiber bundle alterations were consistent with results on regional cortical atrophy. The different anatomical patterns of WM degeneration could provide information on the propagation pathways of distinct proteinopathies.

Latest Perspectives on Alzheimer's Disease Treatment: The Role of Blood-Brain Barrier and Antioxidant-Based Drug Delivery Systems

There has been a growing interest recently in exploring the role of the blood-brain barrier (BBB) in the treatment of Alzheimer's disease (AD), a neurodegenerative disorder characterized by cognitive decline and memory loss that affects millions of people worldwide. Research has shown that the BBB plays a crucial role in regulating the entry of therapeutics into the brain. Also, the potential benefits of using antioxidant molecules for drug delivery were highlighted in Alzheimer's treatment to enhance the therapeutic efficacy and reduce oxidative stress in affected patients. Antioxidant-based nanomedicine shows promise for treating AD by effectively crossing the BBB and targeting neuroinflammation, potentially slowing disease progression and improving cognitive function. Therefore, new drug delivery systems are being developed to overcome the BBB and improve the delivery of therapeutics to the brain, ultimately improving treatment outcomes for AD patients. In this context, the present review provides an in-depth analysis of recent advancements in AD treatment strategies, such as silica nanoparticles loaded with curcumin, selenium nanoparticles loaded with resveratrol, and many others, focusing on the critical role of the BBB and the use of antioxidant-based drug delivery systems.

Burden of non-motor symptoms of Parkinson's disease: cost-of-illness and quality-of-life estimates through a scoping review

INTRODUCTION

Parkinson's Disease (PD) is a progressive, chronic neurodegenerative disease, representing significant economic and social burdens. It is typically defined by motor symptoms (MSs), however, this does not reflect the full patient burden. Non-motor symptoms (NMSs) are increasingly recognized as central characteristics of PD. However, they still lack recognition in research. Therefore, this study aims to identify relevant NMSs, their prevalence, and the effect they have on Quality-of-Life (QoL) and Cost-of-Illness (COI). Secondly, it aims to identify gaps in the current body of knowledge and propose possible ways future research could bridge those gaps.

METHODS

The study employed a scoping review, identifying 60 records for inclusion, using PubMed and Web of Science. It included studies from Spain or Italy, including data on People with Parkinson's Disease. A comparative analysis was performed using Microsoft Excel.

RESULTS

It showed that the body of evidence relevant to NMSs, their prevalence, QoL, and COI is limited, or that estimates vary to an extent where interpretation is difficult.

CONCLUSION

Most studies suffer from generalization, representation, and standardization issues, stemming from their designs and methodological decisions. Although the findings of this study should be interpreted with caution, several recommendations are made for future research.

Propagation of distinct CWD prion strains during peripheral and intracerebral challenges of gene-targeted mice

Since prion diseases result from infection and neurodegeneration of the central nervous system (CNS), experimental characterizations of prion strain properties customarily rely on the outcomes of intracerebral challenges. However, natural transmission of certain prions, including those causing chronic wasting disease (CWD) in elk and deer, depends on propagation in peripheral host compartments prior to CNS infection. Using gene-targeted GtE and GtQ mice, which accurately control cellular elk or deer PrP expression, we assessed the impact that peripheral or intracerebral exposures play on CWD prion strain propagation and resulting CNS abnormalities. Whereas oral and intraperitoneal transmissions produced identical neuropathological outcomes in GtE and GtQ mice and preserved the naturally convergent conformations of elk and deer CWD prions, intracerebral transmissions generated CNS prion strains with divergent biochemical properties in GtE and GtQ mice that were changed compared to their native counterparts. While CWD replication kinetics remained constant during iterative peripheral transmissions and brain titers reflected those found in native hosts, serial intracerebral transmissions produced 10-fold higher prion titers and accelerated incubation times. Our demonstration that peripherally and intracerebrally challenged Gt mice develop dissimilar CNS diseases which result from the propagation of distinct CWD prion strains points to the involvement of tissue-specific cofactors during strain selection in different host compartments. Since peripheral transmissions preserved the natural features of elk and deer prions, whereas intracerebral propagation produced divergent strains, our findings illustrate the importance of experimental characterizations using hosts that not only abrogate species barriers but also accurately recapitulate natural transmission routes of native strains.

Intracerebral inoculation of healthy non-transgenic rats with a single aliquot of oligomeric amyloid-β (1-42) profoundly and progressively alters brain function throughout life

One of the puzzling aspects of sporadic Alzheimer's disease (AD) is how it commences. Changes in one key brain peptide, amyloid-beta (Aβ), accompany disease progression, but whether this comprises a trigger or a consequence of AD is still a topic of debate. It is clear however that the cerebral presence of oligomeric Aβ (1-42) is a key factor in early AD-pathogenesis. Furthermore, treatment of rodent brains with oligomeric Aβ (1-42) either in vitro or in vivo, acutely impairs hippocampal synaptic plasticity, creating a link between Aβ-pathology and learning impairments. Here, we show that a once-off inoculation of the brains of healthy adult rats with oligomeric Aβ (1-42) exerts debilitating effects on the long-term viability of the hippocampus, one of the primary targets of AD. Changes are progressive: months after treatment, synaptic plasticity, neuronal firing and spatial learning are impaired and expression of plasticity-related proteins are changed, in the absence of amyloid plaques. Early changes relate to activation of microglia, whereas later changes are associated with a reconstruction of astroglial morphology. These data suggest that a disruption of Aβ homeostasis may suffice to trigger an irreversible cascade, underlying progressive loss of hippocampal function, that parallels the early stages of AD.

Meta-analysis of the relationship between the number and location of perivascular spaces in the brain and cognitive function

BACKGROUND

Cerebral perivascular spaces are part of the cerebral microvascular structure and play a role in lymphatic drainage and the removal of waste products from the brain. Relationships of the number and location of such spaces with cognition are unclear.

OBJECTIVE

To meta-analyze available data on potential associations of severity and location of perivascular spaces with cognitive performance.

METHODS

We searched PubMed, EMBASE, Web of Science and the Cochrane Central Registry of Controlled Trials for relevant studies published between January 2000 and July 2023. Performance on different cognitive domains was compared to the severity of perivascular spaces in different brain regions using comprehensive meta-analysis. When studies report unadjusted and adjusted means, we use adjusted means for meta-analysis. The study protocol is registered in the PROSPERO database (CRD42023443460).

RESULTS

We meta-analyzed data from 26 cross-sectional studies and two longitudinal studies involving 7908 participants. In most studies perivascular spaces was using a visual rating scale. A higher number of basal ganglia perivascular spaces was linked to lower general intelligence and attention. Moreover, increased centrum semiovale perivascular spaces were associated with worse general intelligence, executive function, language, and memory. Conversely, higher hippocampus perivascular spaces were associated with enhanced memory and executive function. Subgroup analyses revealed variations in associations among different disease conditions.

CONCLUSIONS

A higher quantity of perivascular spaces in the brain is correlated with impaired cognitive function. The location of these perivascular spaces and the underlying disease conditions may influence the specific cognitive domains that are affected.

SYSTEMATIC REVIEW REGISTRATION

The study protocol has been registered in the PROSPERO database (CRD42023443460).

VAMP2 chaperones α-synuclein in synaptic vesicle co-condensates

α-Synuclein (α-Syn) aggregation is closely associated with Parkinson's disease neuropathology. Physiologically, α-Syn promotes synaptic vesicle (SV) clustering and soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex assembly. However, the underlying structural and molecular mechanisms are uncertain and it is not known whether this function affects the pathological aggregation of α-Syn. Here we show that the juxtamembrane region of vesicle-associated membrane protein 2 (VAMP2)-a component of the SNARE complex that resides on SVs-directly interacts with the carboxy-terminal region of α-Syn through charged residues to regulate α-Syn's function in clustering SVs and promoting SNARE complex assembly by inducing a multi-component condensed phase of SVs, α-Syn and other components. Moreover, VAMP2 binding protects α-Syn against forming aggregation-prone oligomers and fibrils in these condensates. Our results suggest a molecular mechanism that maintains α-Syn's function and prevents its pathological amyloid aggregation, the failure of which may lead to Parkinson's disease.

Transcellular transmission and molecular heterogeneity of aggregation-prone proteins in neurodegenerative diseases

The accumulation of aggregation-prone proteins in a specific neuronal population is a common feature of neurodegenerative diseases, which is correlated with the development of pathological lesions in diseased brains. The formation and progression of pathological protein aggregates in susceptible neurons induce cellular dysfunction, resulting in progressive degeneration. Moreover, recent evidence supports the notion that the cell-to-cell transmission of pathological protein aggregates may be involved in the onset and progression of many neurodegenerative diseases. Indeed, several studies have identified different pathological aggregate strains. Although how these different aggregate strains form remains unclear, a variety of biomolecular compositions or cross-seeding events promoted by the presence of other protein aggregates in the cellular environment may affect the formation of different strains of pathological aggregates, which in turn can influence complex pathologies in diseased brains. In this review, we summarize the recent results regarding cell-to-cell transmission and the molecular heterogeneity of pathological aggregate strains, raising key questions for future research directions.

Clinical spreading of muscle weakness in amyotrophic lateral sclerosis (ALS): a study in 910 patients

BACKGROUND

Neuroanatomical staging of sporadic amyotrophic lateral sclerosis (ALS) indicates that neurodegeneration may spread corticofugally.

METHODS

We conducted an observational study to define the initial sites of disease onset and the clinical progression ('spreading patterns') of motor deficits in a cohort of 910 ALS patients in Germany.

RESULTS

Mean age of ALS onset was 59.0 ± 12.6 years for males and 61.2 ± 10.5 years for females, the mean ALSFRS-R was 35.1 ± 9.2, and 7.7% of the cohort reported a family history. Onset of motor symptoms was bulbar/upper limb in 26.8%/35.9%, the right arm initially being slightly more often affected than the left (18.5% vs.16.3%). Testing on concordance of handedness and onset in the dominant arm did not reach significance. Lower limb onset was observed in 37.3%. Unilateral limb onset patients reported horizontal spreading about three times more often than vertical spreading. 71/244 bulbar onset patients reported spreading pattern to the legs, and 17/339 lumbar onset patients reported spreading secondarily to the bulbar region.

DISCUSSION

Our results indicate that, although the phenotype of so-called 'spinal' or 'intraspinal' spreading predominated, we also observed an additional clinical spreading pattern: 29.1% of patients with bulbar onset experienced spreading clinically to the legs (vice versa in 5.0% of lumbar onset patients). For obvious neuroanatomical reasons, this pattern hardly can be explained solely by a 'spinal' or an 'intraspinal' pattern of spreading. Instead, these findings complement insights from previous clinical and clinicopathological studies supporting a cortical initiation of ALS.

Neuroanatomical and cognitive biomarkers of alpha-synuclein propagation in a mouse model of synucleinopathy prior to onset of motor symptoms

Significant evidence suggests that misfolded alpha-synuclein (aSyn), a major component of Lewy bodies, propagates in a prion-like manner contributing to disease progression in Parkinson's disease (PD) and other synucleinopathies. In fact, timed inoculation of M83 hemizygous mice with recombinant human aSyn preformed fibrils (PFF) has shown symptomatic deficits after substantial spreading of pathogenic alpha-synuclein, as detected by markers for the phosphorylation of S129 of aSyn. However, whether accumulated toxicity impact human-relevant cognitive and structural neuroanatomical measures is not fully understood. Here we performed a single unilateral striatal PFF injection in M83 hemizygous mice, and using two assays with translational potential, ex vivo magnetic resonance imaging (MRI) and touchscreen testing, we examined the combined neuroanatomical and behavioral impact of aSyn propagation. In PFF-injected mice, we observed widespread atrophy in bilateral regions that project to or receive input from the injection site using MRI. We also identified early deficits in reversal learning prior to the emergence of motor symptoms. Our findings highlight a network of regions with related cellular correlates of pathology that follow the progression of aSyn spreading, and that affect brain areas relevant for reversal learning. Our experiments suggest that M83 hemizygous mice injected with human PFF provides a model to understand how misfolded aSyn affects human-relevant pre-clinical measures and suggest that these pre-clinical biomarkers could be used to detect early toxicity of aSyn and provide better translational measures between mice and human disease.

Understanding the complex interplay between tau, amyloid and the network in the spatiotemporal progression of Alzheimer's Disease

INTRODUCTION

The interaction of amyloid and tau in neurodegenerative diseases is a central feature of AD pathophysiology. While experimental studies point to various interaction mechanisms, their causal direction and mode (local, remote or network-mediated) remain unknown in human subjects. The aim of this study was to compare mathematical reaction-diffusion models encoding distinct cross-species couplings to identify which interactions were key to model success.

METHODS

We tested competing mathematical models of network spread, aggregation, and amyloid-tau interactions on publicly available data from ADNI.

RESULTS

Although network spread models captured the spatiotemporal evolution of tau and amyloid in human subjects, the model including a one-way amyloid-to-tau aggregation interaction performed best.

DISCUSSION

This mathematical exposition of the "pas de deux" of co-evolving proteins provides quantitative, whole-brain support to the concept of amyloid-facilitated-tauopathy rather than the classic amyloid-cascade or pure-tau hypotheses, and helps explain certain known but poorly understood aspects of AD.

Multiple aspects of amyloid dynamics in vivo integrate to establish prion variant dominance in yeast

Prion variants are self-perpetuating conformers of a single protein that assemble into amyloid fibers and confer unique phenotypic states. Multiple prion variants can arise, particularly in response to changing environments, and interact within an organism. These interactions are often competitive, with one variant establishing phenotypic dominance over the others. This dominance has been linked to the competition for non-prion state protein, which must be converted to the prion state via a nucleated polymerization mechanism. However, the intrinsic rates of conversion, determined by the conformation of the variant, cannot explain prion variant dominance, suggesting a more complex interaction. Using the yeast prion system [PSI+ ], we have determined the mechanism of dominance of the [PSI+ ]Strong variant over the [PSI+ ]Weak variant in vivo. When mixed by mating, phenotypic dominance is established in zygotes, but the two variants persist and co-exist in the lineage descended from this cell. [PSI+ ]Strong propagons, the heritable unit, are amplified at the expense of [PSI+ ]Weak propagons, through the efficient conversion of soluble Sup35 protein, as revealed by fluorescence photobleaching experiments employing variant-specific mutants of Sup35. This competition, however, is highly sensitive to the fragmentation of [PSI+ ]Strong amyloid fibers, with even transient inhibition of the fragmentation catalyst Hsp104 promoting amplification of [PSI+ ]Weak propagons. Reducing the number of [PSI+ ]Strong propagons prior to mating, similarly promotes [PSI+ ]Weak amplification and conversion of soluble Sup35, indicating that template number and conversion efficiency combine to determine dominance. Thus, prion variant dominance is not an absolute hierarchy but rather an outcome arising from the dynamic interplay between unique protein conformations and their interactions with distinct cellular proteostatic niches.

Modulation of Alzheimer's Disease Aβ40 Fibril Polymorphism by the Small Heat Shock Protein αB-Crystallin

Deposition of amyloid plaques in the brains of Alzheimer's disease (AD) patients is a hallmark of the disease. AD plaques consist primarily of the beta-amyloid (Aβ) peptide but can contain other factors such as lipids, proteoglycans, and chaperones. So far, it is unclear how the cellular environment modulates fibril polymorphism and how differences in fibril structure affect cell viability. The small heat-shock protein (sHSP) alpha-B-Crystallin (αBC) is abundant in brains of AD patients, and colocalizes with Aβ amyloid plaques. Using solid-state NMR spectroscopy, we show that the Aβ40 fibril seed structure is not replicated in the presence of the sHSP. αBC prevents the generation of a compact fibril structure and leads to the formation of a new polymorph with a dynamic N-terminus. We find that the N-terminal fuzzy coat and the stability of the C-terminal residues in the Aβ40 fibril core affect the chemical and thermodynamic stability of the fibrils and influence their seeding capacity. We believe that our results yield a better understanding of how sHSP, such as αBC, that are part of the cellular environment, can affect fibril structures related to cell degeneration in amyloid diseases.

The importance of prion research

Over the past four decades, prion diseases have received considerable research attention owing to their potential to be transmitted within and across species as well as their consequences for human and animal health. The unprecedented nature of prions has led to the discovery of a paradigm of templated protein misfolding that underlies a diverse range of both disease-related and normal biological processes. Indeed, the "prion-like" misfolding and propagation of protein aggregates is now recognized as a common underlying disease mechanism in human neurodegenerative disorders such as Alzheimer's and Parkinson's disease, and the prion principle has led to the development of novel diagnostic and therapeutic strategies for these illnesses. Despite these advances, research into the fundamental biology of prion diseases has declined, likely due to their rarity and the absence of an acute human health crisis. Given the past translational influence, continued research on the etiology, pathogenesis, and transmission of prion disease should remain a priority. In this review, we highlight several important "unsolved mysteries" in the prion disease research field and how solving them may be crucial for the development of effective therapeutics, preventing future outbreaks of prion disease, and understanding the pathobiology of more common human neurodegenerative disorders.

Neuromodulation modifies α-synuclein spreading dynamics in vivo and the pattern is predicted by changes in whole-brain function

BACKGROUND

Many neurodegenerative disease treatments, such as deep brain stimulation for Parkinson's Disease, can alleviate symptoms by primarily compensating for circuit dysfunctions. However, the stimulation's effect on the underlying disease progression remains relatively unknown. Here, we report that neuromodulation can not only modulate circuit function but also modulate the in vivo spreading dynamics of α-synuclein pathology, the primary pathological hallmark observed in Parkinson's Disease.

METHODS

In a mouse model, pre-formed fibrils were injected into the striatum to induce widespread α-synuclein pathology. Two days after fibril injection, mice were treated for two weeks with daily optogenetic stimulation of the Secondary Motor Area, Layer V. Whole brains were then extracted, immunolabeled, cleared, and imaged with light-sheet fluorescent microscopy.

RESULTS

Repeated optogenetic stimulation led to a decrease in pathology at the site of stimulation and at various cortical and subcortical regions, while the contralateral cortex saw a consistent increase. Aligning the pathology changes with optogenetic-fMRI measured brain activity, we found that the changes in pathology and brain function had similar spatial locations but opposite polarity.

CONCLUSION

These results demonstrate the ability to modulate and predict whole brain pathology changes using neuromodulation, opening a new horizon for investigating optimized neuromodulation therapies.

Chemically reactive and aging macromolecular mixtures I: Phase diagrams, spinodals, and gelation

Multicomponent macromolecular mixtures often form higher-order structures, which may display non-ideal mixing and aging behaviors. In this work, we first propose a minimal model of a quaternary system that takes into account the formation of a complex via a chemical reaction involving two macromolecular species; the complex may then phase separate from the buffer and undergo a further transition into a gel-like state. We subsequently investigate how physical parameters such as molecular size, stoichiometric coefficients, equilibrium constants, and interaction parameters affect the phase behavior of the mixture and its propensity to undergo aging via gelation. In addition, we analyze the thermodynamic stability of the system and identify the spinodal regions and their overlap with gelation boundaries. The approach developed in this work can be readily generalized to study systems with an arbitrary number of components. More broadly, it provides a physically based starting point for the investigation of the kinetics of the coupled complex formation, phase separation, and gelation processes in spatially extended systems.

Anti-acetylated-tau immunotherapy is neuroprotective in tauopathy and brain injury

BACKGROUND

Tau is aberrantly acetylated in various neurodegenerative conditions, including Alzheimer's disease, frontotemporal lobar degeneration (FTLD), and traumatic brain injury (TBI). Previously, we reported that reducing acetylated tau by pharmacologically inhibiting p300-mediated tau acetylation at lysine 174 reduces tau pathology and improves cognitive function in animal models.

METHODS

We investigated the therapeutic efficacy of two different antibodies that specifically target acetylated lysine 174 on tau (ac-tauK174). We treated PS19 mice, which harbor the P301S tauopathy mutation that causes FTLD, with anti-ac-tauK174 and measured effects on tau pathology, neurodegeneration, and neurobehavioral outcomes. Furthermore, PS19 mice received treatment post-TBI to evaluate the ability of the immunotherapy to prevent TBI-induced exacerbation of tauopathy phenotypes. Ac-tauK174 measurements in human plasma following TBI were also collected to establish a link between trauma and acetylated tau levels, and single nuclei RNA-sequencing of post-TBI brain tissues from treated mice provided insights into the molecular mechanisms underlying the observed treatment effects.

RESULTS

Anti-ac-tauK174 treatment mitigates neurobehavioral impairment and reduces tau pathology in PS19 mice. Ac-tauK174 increases significantly in human plasma 24 h after TBI, and anti-ac-tauK174 treatment of PS19 mice blocked TBI-induced neurodegeneration and preserved memory functions. Anti-ac-tauK174 treatment rescues alterations of microglial and oligodendrocyte transcriptomic states following TBI in PS19 mice.

CONCLUSIONS

The ability of anti-ac-tauK174 treatment to rescue neurobehavioral impairment, reduce tau pathology, and rescue glial responses demonstrates that targeting tau acetylation at K174 is a promising neuroprotective therapeutic approach to human tauopathies resulting from TBI or genetic disease.

Transmissible long-term neuroprotective and pro-cognitive effects of 1-42 beta-amyloid with A2T icelandic mutation in an Alzheimer's disease mouse model

The amyloid cascade hypothesis assumes that the development of Alzheimer's disease (AD) is driven by a self-perpetuating cycle, in which β-amyloid (Aβ) accumulation leads to Tau pathology and neuronal damages. A particular mutation (A673T) of the amyloid precursor protein (APP) was identified among Icelandic population. It provides a protective effect against Alzheimer- and age-related cognitive decline. This APP mutation leads to the reduced production of Aβ with A2T (position in peptide sequence) change (Aβice). In addition, Aβice has the capacity to form protective heterodimers in association with wild-type Aβ. Despite the emerging interest in Aβice during the last decade, the impact of Aβice on events associated with the amyloid cascade has never been reported. First, the effects of Aβice were evaluated in vitro by electrophysiology on hippocampal slices and by studying synapse morphology in cortical neurons. We showed that Aβice protects against endogenous Aβ-mediated synaptotoxicity. Second, as several studies have outlined that a single intracerebral administration of Aβ can worsen Aβ deposition and cognitive functions several months after the inoculation, we evaluated in vivo the long-term effects of a single inoculation of Aβice or Aβ-wild-type (Aβwt) in the hippocampus of transgenic mice (APPswe/PS1dE9) over-expressing Aβ1-42 peptide. Interestingly, we found that the single intra-hippocampal inoculation of Aβice to mice rescued synaptic density and spatial memory losses four months post-inoculation, compared with Aβwt inoculation. Although Aβ load was not modulated by Aβice infusion, the amount of Tau-positive neuritic plaques was significantly reduced. Finally, a lower phagocytosis by microglia of post-synaptic compounds was detected in Aβice-inoculated animals, which can partly explain the increased density of synapses in the Aβice animals. Thus, a single event as Aβice inoculation can improve the fate of AD-associated pathology and phenotype in mice several months after the event. These results open unexpected fields to develop innovative therapeutic strategies against AD.

Advancing Parkinson's Disease Diagnostics: The Potential of Arylpyrazolethiazole Derivatives for Imaging α-Synuclein Aggregates

The development of positron emission tomography (PET) tracers capable of detecting α-synuclein (α-syn) aggregates in vivo would represent a breakthrough for advancing the understanding and enabling the early diagnosis of Parkinson's disease and related disorders. It also holds the potential to assess the efficacy of therapeutic interventions. However, this remains challenging due to different structures of α-syn aggregates, the need for selectivity over other structurally similar amyloid proteins, like amyloid-β (Aβ), which frequently coexist with α-syn pathology, and the low abundance of the target in the brain that requires the development of a high-affinity ligand. To develop a successful PET tracer for the central nervous system (CNS), stringent criteria in terms of polarity and molecular size must also be considered, as the tracer must penetrate the blood-brain barrier and have low nonspecific binding to brain tissue. Here, we report a series of arylpyrazolethiazole (APT) derivatives, rationally designed from a structure-activity relationship study centered on existing ligands for α-syn fibrils, with a particular focus on the selectivity toward α-syn fibrils and control of physicochemical properties suitable for a CNS PET tracer. In vitro competition binding assays performed against [3H]MODAG-001 using recombinant α-syn and Aβ1-42 fibrils revealed APT-13 with an inhibition constant of 27.8 ± 9.7 nM and a selectivity of more than 3.3 fold over Aβ. Radiolabeled [11C]APT-13 demonstrated excellent brain penetration in healthy mice with a peak standardized uptake value of 1.94 ± 0.29 and fast washout from the brain (t 1/2 = 9 ± 1 min). This study highlights the potential of APT-13 as a lead compound for developing PET tracers to detect α-syn aggregates in vivo.

Frontotemporal dementia-like disease progression elicited by seeded aggregation and spread of FUS

RNA binding proteins have emerged as central players in the mechanisms of many neurodegenerative diseases. In particular, a proteinopathy of fused in sarcoma (FUS) is present in some instances of familial Amyotrophic lateral sclerosis (ALS) and about 10% of sporadic Frontotemporal lobar degeneration (FTLD). Here we establish that focal injection of sonicated human FUS fibrils into brains of mice in which ALS-linked mutant or wild-type human FUS replaces endogenous mouse FUS is sufficient to induce focal cytoplasmic mislocalization and aggregation of mutant and wild-type FUS which with time spreads to distal regions of the brain. Human FUS fibril-induced FUS aggregation in the mouse brain of humanized FUS mice is accelerated by an ALS-causing FUS mutant relative to wild-type human FUS. Injection of sonicated human FUS fibrils does not induce FUS aggregation and subsequent spreading after injection into naïve mouse brains containing only mouse FUS, indicating a species barrier to human FUS aggregation and its prion-like spread. Fibril-induced human FUS aggregates recapitulate pathological features of FTLD including increased detergent insolubility of FUS and TAF15 and amyloid-like, cytoplasmic deposits of FUS that accumulate ubiquitin and p62, but not TDP-43. Finally, injection of sonicated FUS fibrils is shown to exacerbate age-dependent cognitive and behavioral deficits from mutant human FUS expression. Thus, focal seeded aggregation of FUS and further propagation through prion-like spread elicits FUS-proteinopathy and FTLD-like disease progression.

Frontotemporal dementia-like disease progression elicited by seeded aggregation and spread of FUS

RNA binding proteins have emerged as central players in the mechanisms of many neurodegenerative diseases. In particular, a proteinopathy of fu sed in s arcoma (FUS) is present in some instances of familial Amyotrophic lateral sclerosis (ALS) and about 10% of sporadic FTLD. Here we establish that focal injection of sonicated human FUS fibrils into brains of mice in which ALS-linked mutant or wild-type human FUS replaces endogenous mouse FUS is sufficient to induce focal cytoplasmic mislocalization and aggregation of mutant and wild-type FUS which with time spreads to distal regions of the brain. Human FUS fibril-induced FUS aggregation in the mouse brain of humanized FUS mice is accelerated by an ALS-causing FUS mutant relative to wild-type human FUS. Injection of sonicated human FUS fibrils does not induce FUS aggregation and subsequent spreading after injection into naïve mouse brains containing only mouse FUS, indicating a species barrier to human FUS aggregation and its prion-like spread. Fibril-induced human FUS aggregates recapitulate pathological features of FTLD including increased detergent insolubility of FUS and TAF15 and amyloid-like, cytoplasmic deposits of FUS that accumulate ubiquitin and p62, but not TDP-43. Finally, injection of sonicated FUS fibrils is shown to exacerbate age-dependent cognitive and behavioral deficits from mutant human FUS expression. Thus, focal seeded aggregation of FUS and further propagation through prion-like spread elicits FUS-proteinopathy and FTLD-like disease progression.

Αnti-prion effects of anthocyanins

Prion diseases, also known as Transmissible Spongiform Encephalopathies (TSEs), are protein-based neurodegenerative disorders (NDs) affecting humans and animals. They are characterized by the conformational conversion of the normal cellular prion protein, PrPC, into the pathogenic isoform, PrPSc. Prion diseases are invariably fatal and despite ongoing research, no effective prophylactic or therapeutic avenues are currently available. Anthocyanins (ACNs) are unique flavonoid compounds and interest in their use as potential neuroprotective and/or therapeutic agents against NDs, has increased significantly in recent years. Therefore, we investigated the potential anti-oxidant and anti-prion effects of Oenin and Myrtillin, two of the most common anthocyanins, using the most accepted in the field overexpressing PrPScin vitro model and a cell free protein aggregation model. Our results, indicate both anthocyanins as strong anti-oxidant compounds, upregulating the expression of genes involved in the anti-oxidant response, and reducing the levels of Reactive Oxygen Species (ROS), produced due to pathogenic prion infection, through the activation of the Keap1-Nrf2 pathway. Importantly, they showcased remarkable anti-prion potential, as they not only caused the clearance of pathogenic PrPSc aggregates, but also completely inhibited the formation of PrPSc fibrils in the Cerebrospinal Fluid (CSF) of patients with Creutzfeldt-Jakob disease (CJD). Therefore, Oenin and Myrtillin possess pleiotropic effects, suggesting their potential use as promising preventive and/or therapeutic agents in prion diseases and possibly in the spectrum of neurodegenerative proteinopathies.

Milligram-scale assembly and NMR fingerprint of tau fibrils adopting the Alzheimer's disease fold

In the Alzheimer's disease (AD) brain, the microtubule-associated protein tau aggregates into paired helical filaments in which each protofilament has a C-shaped conformation. In vitro assembly of tau fibrils adopting this fold is highly valuable for both fundamental and applied studies of AD without requiring patient-brain extracted fibrils. To date, reported methods for forming AD-fold tau fibrils have been irreproducible and sensitive to subtle variations in fibrillization conditions. Here, we describe a route to reproducibly assemble tau fibrils adopting the AD fold on the multi-milligram scale. We investigated the fibrillization conditions of two constructs and found that a tau (297-407) construct that contains four AD phospho-mimetic glutamate mutations robustly formed the C-shaped conformation. 2D and 3D correlation solid-state NMR spectra show a single predominant set of chemical shifts, indicating a single molecular conformation. Negative-stain electron microscopy and cryo-EM data confirm that the protofilament formed by 4E-tau (297-407) adopts the C-shaped conformation, which associates into paired, triple, and quadruple helical filaments. In comparison, NMR spectra indicate that a previously reported construct, tau (297-391), forms a mixture of a four-layered dimer structure and the C-shaped structure, whose populations are sensitive to the environmental conditions. The determination of the NMR chemical shifts of the AD-fold tau opens the possibility for future studies of tau fibril conformations and ligand binding by NMR. The quantitative assembly of tau fibrils adopting the AD fold should facilitate the development of diagnostic and therapeutic compounds that target AD tau.

Cognitive Impairment Is Related to Glymphatic System Dysfunction in Pediatric Multiple Sclerosis

OBJECTIVE

The aim of this study was to investigate whether, compared to pediatric healthy controls (HCs), the glymphatic system is impaired in pediatric multiple sclerosis (MS) patients according to their cognitive status, and to assess its association with clinical disability and MRI measures of brain structural damage.

METHODS

Sixty-five pediatric MS patients (females = 62%; median age = 15.5 [interquartile range, IQR = 14.5;17.0] years) and 23 age- and sex-matched HCs (females = 44%; median age = 14.1 [IQR = 11.8;16.2] years) underwent neurological, neuropsychological and 3.0 Tesla MRI assessment, including conventional and diffusion tensor imaging (DTI). We calculated the diffusion along the perivascular space (DTI-ALPS) index, a proxy of glymphatic function. Cognitive impairment (Co-I) was defined as impairment in at least 2 cognitive domains.

RESULTS

No significant differences in DTI-ALPS index were found between HCs and cognitively preserved (Co-P) pediatric MS patients (estimated mean difference [EMD] = -0.002 [95% confidence interval = -0.069; 0.065], FDR-p = 0.956). Compared to HCs and Co-P patients, Co-I pediatric MS patients (n = 20) showed significantly lower DTI-ALPS index (EMD = -0.136 [95% confidence interval = -0.214; -0.058], FDR-p ≤ 0.004). In HCs, no associations were observed between DTI-ALPS index and normalized brain, cortical and thalamic volumes, and normal-appearing white matter (NAWM) fractional anisotropy (FA) and mean diffusivity (MD) (FDR-p ≥ 0.348). In pediatric MS patients, higher brain WM lesion volume (LV), higher NAWM MD, lower normalized thalamic volume, and lower NAWM FA were associated with lower DTI-ALPS index (FDR-p ≤ 0.016). Random Forest selected lower DTI-ALPS index (relative importance [RI] = 100%), higher brain WM LV (RI = 59.5%) NAWM MD (RI = 57.1%) and intelligence quotient (RI = 51.3%) as informative predictors of cognitive impairment (out-of-bag area under the curve = 0.762).

INTERPRETATION

Glymphatic system dysfunction occurs in pediatric MS, is associated with brain focal lesions, irreversible tissue loss accumulation and cognitive impairment. ANN NEUROL 2024;95:1080-1092.

Neurotropic virus infection and neurodegenerative diseases: Potential roles of autophagy pathway

Neurodegenerative diseases (NDs) constitute a group of disorders characterized by the progressive deterioration of nervous system functionality. Currently, the precise etiological factors responsible for NDs remain incompletely elucidated, although it is probable that a combination of aging, genetic predisposition, and environmental stressors participate in this process. Accumulating evidence indicates that viral infections, especially neurotropic viruses, can contribute to the onset and progression of NDs. In this review, emerging evidence supporting the association between viral infection and NDs is summarized, and how the autophagy pathway mediated by viral infection can cause pathological aggregation of cellular proteins associated with various NDs is discussed. Furthermore, autophagy-related genes (ARGs) involved in Herpes simplex virus (HSV-1) infection and NDs are analyzed, and whether these genes could link HSV-1 infection to NDs is discussed. Elucidating the mechanisms underlying NDs is critical for developing targeted therapeutic approaches that prevent the onset and slow the progression of NDs.

Risk of Parkinson's disease in hepatitis B and C populations: a systematic review and meta-analysis

Parkinson's disease (PD) is a common neurodegenerative disorder, and its association with viral hepatitis has been debated. We performed a meta-analysis to examine the association between PD risk and viral hepatitis. Medline, EMBASE, and the Cochrane library were searched from inception till July 2022. Meta-analysis was conducted using a fixed-effect model with the inverse variance method. Three groups were compared to controls: infection with either hepatitis B or C virus (HBV and HCV, respectively), or coinfection with both viruses. We found 551 records, and six studies comprising of 2,566,947 patients were included in the analysis. PD risk was increased in HCV-infected population (OR 1.10, 95% CI 1.03-1.17, p = 0.005) and (HR 1.37, 95% CI 1.26-1.49, p < 0.001). This increase was not observed for the HBV-infected and HBV-HCV-coinfected coinfection populations. For pooled OR, the risk was significantly lower in HBV-infected (OR 0.79, 95% CI 0.76-0.83, p < 0.001) but not significantly different in HBV-HCV-coinfected populations (OR 0.96, 95% CI 0.82-1.12, p = 0.57). For pooled HR, the risk was significantly higher in both HBV-infected (HR 1.22, 95% CI 1.14-1.31, p < 0.001) and HBV-HCV-coinfected populations (HR 1.29, 95% CI 1.05-1.58, p = 0.013). We found that the risk of PD was increased in the HCV-infected population, but results were inconsistent in those with HBV and HBV-HCV infections. Our findings provide impetus for further clinical and functional studies to unravel the role of the adaptive immune system in PD.

High-Yield α-Synuclein Purification and Ionic Strength Modification Pivotal to Seed Amplification Assay Performance and Reproducibility

Alpha-synuclein seed amplification assays (αSyn-SAAs) have emerged as promising diagnostic tools for Parkinson's disease (PD) by detecting misfolded αSyn and amplifying the signal through cyclic shaking and resting in vitro. Recently, our group and others have shown that multiple biospecimens, including CSF, skin, and submandibular glands (SMGs), can be used to seed the aggregation reaction and robustly distinguish between patients with PD and non-disease controls. The ultrasensitivity of the assay affords the ability to detect minute quantities of αSyn in peripheral tissues, but it also produces various technical challenges of variability. To address the problem of variability, we present a high-yield αSyn protein purification protocol for the efficient production of monomers with a low propensity for self-aggregation. We expressed wild-type αSyn in BL21 Escherichia coli, lysed the cells using osmotic shock, and isolated αSyn using acid precipitation and fast protein liquid chromatography (FPLC). Following purification, we optimized the ionic strength of the reaction buffer to distinguish the fluorescence maximum (Fmax) separation between disease and healthy control tissues for enhanced assay performance. Our protein purification protocol yielded high quantities of αSyn (average: 68.7 mg/mL per 1 L of culture) and showed highly precise and robust αSyn-SAA results using brain, skin, and SMGs with inter-lab validation.

Recent Advances in Targeting Transition Metals (Copper, Iron, and Zinc) in Alzheimer's Disease

Changes in the transition metal homeostasis in the brain are closely linked with Alzheimer's disease (AD), including intraneuronal iron accumulation and extracellular copper and zinc pooling in the amyloid plague. The brain copper, zinc, and iron surplus are commonly acknowledged characteristics of AD, despite disagreements among some. This has led to the theory that oxidative stress resulting from abnormal homeostasis of these transition metals may be a causative explanation behind AD. In the nervous system, the interaction of metals with proteins appears to be an essential variable in the development or suppression of neurodegeneration. Chelation treatment may be an option for treating neurodegeneration induced by transition metal ion dyshomeostasis. Some clinicians even recommend using chelating agents as an adjunct therapy for AD. The current review also looks at the therapeutic strategies that have been attempted, primarily with metal-chelating drugs. Metal buildup in the nervous system, as reported in the AD, could be the result of compensatory mechanisms designed to improve metal availability for physiological functions.

Future perspective and clinical applicability of the combined use of plasma phosphorylated tau 181 and neurofilament light chain in Subjective Cognitive Decline and Mild Cognitive Impairment

We aimed to assess diagnostic accuracy of plasma p-tau181 and NfL separately and in combination in discriminating Subjective Cognitive Decline (SCD) and Mild Cognitive Impairment (MCI) patients carrying Alzheimer's Disease (AD) pathology from non-carriers; to propose a flowchart for the interpretation of the results of plasma p-tau181 and NfL. We included 43 SCD, 41 MCI and 21 AD-demented (AD-d) patients, who underwent plasma p-tau181 and NfL analysis. Twenty-eight SCD, 41 MCI and 21 AD-d patients underwent CSF biomarkers analysis (Aβ1-42, Aβ1-42/1-40, p-tau, t-tau) and were classified as carriers of AD pathology (AP+) it they were A+/T+ , or non-carriers (AP-) when they were A-, A+/T-/N-, or A+/T-/N+ according to the A/T(N) system. Plasma p-tau181 and NfL separately showed a good accuracy (AUC = 0.88), while the combined model (NfL + p-tau181) showed an excellent accuracy (AUC = 0.92) in discriminating AP+ from AP- patients. Plasma p-tau181 and NfL results were moderately concordant (Coehn's k = 0.50, p < 0.001). Based on a logistic regression model, we estimated the risk of AD pathology considering the two biomarkers: 10.91% if both p-tau181 and NfL were negative; 41.10 and 76.49% if only one biomarker was positive (respectively p-tau18 and NfL); 94.88% if both p-tau181 and NfL were positive. Considering the moderate concordance and the risk of presenting an underlying AD pathology according to the positivity of plasma p-tau181 and NfL, we proposed a flow chart to guide the combined use of plasma p-tau181 and NfL and the interpretation of biomarker results to detect AD pathology.

Mechanistic study of the anti-excitatory amino acid toxicity of Bushen Zhichan decoction for Parkinson's disease based on the transcriptional regulation of EAAT1 by YY1

ETHNOPHARMACOLOGICAL RELEVANCE

Bushen Zhichan decoction (BSZCF) is derived from Liuwei Dihuang Pill, a famous Chinese herbal formula recorded in the book Key to Therapeutics of Children's Diseases. It has been widely used as a basic prescription for nourishing and tonifying the liver and kidneys to treat Parkinson's disease (PD), but its mechanism remains to be explored.

AIM OF THE STUDY

BSZCF, a Chinese herbal formula comprising five herbs: Rehmannia glutinosa (Gaertn.) DC., Dioscorea oppositifolia L., Cornus officinalis Siebold & Zucc., Fallopia multiflora (Thunb.) Haraldson and Cistanche tubulosa (Schenk) Wight, is used clinically to treat PD. In vivo and in vitro experiments were designed to elucidate the mechanism of BSZCF in the protection of dopamine (DA) neurons and the treatment of PD. The toxicity of excitatory amino acids (EAA) may be attenuated by inhibiting the transcription factor Yin Yang 1 (YY1) and up-regulating the expression of excitatory amino acid transporter 1 (EAAT1).

MATERIALS AND METHODS

IN VIVO: After 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) was intraperitoneally injected into specific pathogen free (SPF) C57BL/6J mice, model mice were intragastrically given adamantane hydrochloride tablets (AHT) or different doses of BSZCF for 14 days. Both open field and pole-climbing tests were conducted to assess behavioral changes. In vitro: 1-Methyl-4-phe-nylpyridiniumiodide (MPP+)-injured human neuroblastoma cells (SH-SY5Y) were utilized to construct PD cell models. Primary astrocytes were transfected with EAAT1 and YY1 lentiviruses for EAAT1 gene knockout and YY1 gene knockout astrocytes, respectively. The high performance liquid chromatography-mass spectrometry (HPLC-MS) analysis of BSZCF was performed to control the quality of blood drugs. The optimal concentration and time of PD cell models treated by BSZCF were determined by the use of Cell Counting Kit-8 (CCK8). Enzyme-linked immunosorbent assay (ELISA) was used for measuring glutamate (Glu) in the peripheral blood and cells of each group. Western blotting (WB) and real-time quantitative polymerase chain reaction (qPCR) were used to detect tyrosine hydroxylase (TH), dopamine transporters (DAT), EAAT1 and YY1 protein and mRNA. After the blockade of EAAT1, immunofluorescence (IF) assay was used to detect the TH protein in each group.

RESULTS

In vivo research showed that BSZCF improved the behavioral symptoms of PD mice, and reduced the death of DA neurons and the level of Glu. The mechanism may be related to the decrease of YY1 expression and the increase of EAAT1 levels. In vitro experiments showed that the anti-excitatory amino acid toxicity of BSZCF was achieved by inhibiting YY1 expression and regulating EAAT1.

CONCLUSIONS

By inhibiting YY1 to increase the expression of EAAT1 and attenuating the toxicity of Glu, BSZCF exerts the effect of protecting DA neurons and treating PD-like symptoms in mice.

Endothelial cellular senescence and tau accumulation: An interplay full of opportunities?

Recent research has shown that tau protein can be passed to neighboring cells, leading to cellular senescence in the endothelial cells present in the central nervous system (CNS). This discovery could potentially open new doors for testing novel therapeutic compounds that specifically target senescent cells (senolytics) or for identifying new biomarkers that can enable early detection of tauopathies and dementia.

Prevention of amyloid β fibril deposition on the synaptic membrane in the precuneus by ganglioside nanocluster-targeting inhibitors

Alzheimer's disease (AD), a progressive neurodegenerative condition, is one of the most common causes of dementia. Senile plaques, a hallmark of AD, are formed by the accumulation of amyloid β protein (Aβ), which starts to aggregate before the onset of the disease. Gangliosides, sialic acid-containing glycosphingolipids, play a key role in the formation of toxic Aβ aggregates. In membrane rafts, ganglioside-bound complexes (GAβ) act as nuclei for Aβ assembly, suggesting that GAβ is a promising target for AD therapy. The formation of GAβ-induced Aβ assemblies has been evaluated using reconstituted planar lipid membranes composed of synaptosomal plasma membrane (SPM) lipids extracted from human and mouse brains. Although the effects of gangliosides on Aβ accumulation in the precuneus have been established, effects on Aβ fibrils have not been determined. In this study, Aβ42 fibrils on reconstituted membranes composed of SPM lipids prepared from the precuneus cortex of human autopsied brains were evaluated by atomic force microscopy. In particular, Aβ42 accumulation, as well as the fibril number and size were higher for membranes with precuneus lipids than for membranes with calcarine cortex lipids. In addition, artificial peptide inhibitors targeting Aβ-sensitive ganglioside nanoclusters cleared Aβ assemblies on synaptic membranes in the brain, providing a novel therapeutic strategy for AD.

Mismatch between clinically defined classification of ALS stage and the burden of cerebral pathology

This study aimed to investigate the clinical stratification of amyotrophic lateral sclerosis (ALS) patients in relation to in vivo cerebral degeneration. One hundred forty-nine ALS patients and one hundred forty-four healthy controls (HCs) were recruited from the Canadian ALS Neuroimaging Consortium (CALSNIC). Texture analysis was performed on T1-weighted scans to extract the texture feature "autocorrelation" (autoc), an imaging biomarker of cerebral degeneration. Patients were stratified at baseline into early and advanced disease stages based on criteria adapted from ALS clinical trials and the King's College staging system, as well as into slow and fast progressors (disease progression rates, DPR). Patients had increased autoc in the internal capsule. These changes extended beyond the internal capsule in early-stage patients (clinical trial-based criteria), fast progressors, and in advanced-stage patients (King's staging criteria). Longitudinal increases in autoc were observed in the postcentral gyrus, corticospinal tract, posterior cingulate cortex, and putamen; whereas decreases were observed in corpus callosum, caudate, central opercular cortex, and frontotemporal areas. Both longitudinal increases and decreases of autoc were observed in non-overlapping regions within insula and precentral gyrus. Within-criteria comparisons of autoc revealed more pronounced changes at baseline and longitudinally in early- (clinical trial-based criteria) and advanced-stage (King's staging criteria) patients and fast progressors. In summary, comparative patterns of baseline and longitudinal progression in cerebral degeneration are dependent on sub-group selection criteria, with clinical trial-based stratification insufficiently characterizing disease stage based on pathological cerebral burden.