Saima Zafar

The conversion of native prion protein (PrP) into its misfolded isoform, scrapie (PrPSc) and its intracellular accumulation represent central events in the pathogenesis of prion diseases. Reduction of native PrP in the central nervous system (CNS) has emerged as a promising strategy for treatment and prevention of prion diseases in humans. To facilitate translation into clinical practice, it is essential to identify at-risk individuals through biomarker development and to elucidate PrP behaviour across prion disease subtypes and biological fluids. Measurements of PrP in accessible biofluids, such as plasma and cerebrospinal fluid (CSF), may provide a pharmacodynamic readout and enable monitoring for PrP-targeted therapies. This study systematically quantifies PrP in plasma and CSF of individuals with sporadic and genetic prion diseases, healthy controls (HC), patients with non-neurodegenerative neurological conditions (ND) and Alzheimer’s disease (AD). We analysed 136 plasma and 84 CSF samples, including HC, AD, sporadic Creutzfeldt–Jakob disease (sCJD), as well as symptomatic patients and asymptomatic carriers of the mutations D178N, E200K and P102L. Quantification of PrP was performed using a BetaPrion Human ELISA. Statistical analyses assessed differences between diagnostic groups, associations with demographic factors and PRNP codon 129 polymorphism, and diagnostic accuracy via ROC curves. Plasma PrP was significantly reduced in patients with sCJD (P = 0.043), in symptomatic patients with the E200K (P = 0.0078) and in both symptomatic and asymptomatic D178N carriers (P = 0.0002) compared to HC. Furthermore, symptomatic and asymptomatic D178N carriers had significantly lower plasma PrP levels than patients with AD (P = 0.0025 and P = 0.0041, respectively). In CSF, PrP concentrations were notably lower in D178N symptomatic patients (P = 0.0026) versus non-neurodegenerative (ND) controls. Plasma PrP levels showed no association with age, sex or disease onset and were lower in genetic prion disease patients with the methionine/valine (MV) genotype at PRNP codon 129. The diagnostic accuracy for PrP quantification in plasma as a biomarker discriminated D178N asymptomatic carriers [area under the curve (AUC) = 0.96] and D178N symptomatic patients (AUC = 0.90) from HC with excellent accuracy. In CSF, PrP quantification discriminated D178N symptomatic patients from ND with good accuracy (AUC = 0.64). Taken together, this study defines a characteristic profile of persistently low plasma and CSF PrP in D178N symptomatic and asymptomatic mutation carriers. Low plasma levels in sCJD and E200K, in contrast to P102L, are puzzling. Mutation-specific patterns of PrP need to be considered for monitoring purposes in clinical trials.

Parkinson’s disease (PD) is a neurodegenerative disorder marked by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta, leading to significant motor dysfunction. Current treatments stabilize dopamine levels but fail to address underlying neuronal apoptosis, highlighting the need for novel approaches. Although chrysoeriol, a 3’-O-methoxy flavone and luteolin derivative, is well-documented for its anti-cancer, anti-diabetic, antioxidant, and anti-inflammatory properties, its neuroprotective potential in PD, particularly in vivo, remains largely unexplored. This study fills a critical gap by being the first to systematically assess chrysoeriol’s neuroprotective effects in a PD mouse model. We evaluated the effects of 5 mg/kg chrysoeriol administered intraperitoneally (IP) for 14 days in an acute 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD model. Behavioral tests showed notable recovery, as chrysoeriol eliminated deficits in motor function, coordination, and balance, as assessed by the pole test, forced swim test, and tail suspension test. It also mitigated exploratory and locomotor deficits in the open field test, and the Y-maze test revealed improved spatial and learning memory. Hematoxylin and eosin staining indicated a significant reduction in neuronal damage across key brain regions. qPCR analysis showed reduced 1-methyl-4-phenylpyridinium (MPP+)-induced toxicity, downregulation of α-synuclein, and an improved Bcl-2/Bax ratio. These findings suggest chrysoeriol may protect against MPP+-induced apoptosis in mice, potentially via the PI3K/Akt signaling pathway, and reduces mitochondrial damage by downregulating α-synuclein.

Background: TIA-1 (T-cell intracellular antigen 1) is an RNA-binding protein central to the formation of stress granules (SGs) and modulation of inflammatory responses. Recent research has identified TIA-1 as a key player in neurodegenerative diseases, especially those involving Tau pathology such as in Alzheimer’s disease (AD), in a subtype-dependent manner. Disease-modifying therapies for AD and related dementias are emerging, but their effectiveness hinges on timely and accurate diagnosis. This underscores urgent need for easily accessible and reliable blood biomarkers for early detection, disease monitoring, and subtype differentiation. Methods: Accordingly, in this pilot study, we evaluated the plasma TIA-1 levels in healthy controls and across spectrum of neurodegenerative diseases to assess its clinical and biological significance. Plasma TIA-1 concentrations were measured in Alzheimer’s disease, mild cognitive impairment due to AD (MCI-AD), vascular cognitive impairment (VCI), and other neurodegenerative diseases (NDs: synucleinopathies and tauopathies), and compared to healthy controls. Receiver operating characteristic (ROC) analyses and correlation studies with established biomarkers and cognitive scores were performed. Results: Plasma TIA-1 levels were significantly reduced in AD, MCI-AD, VCI, and non-AD neurodegenerative diseases (synucleinopathies and tauopathies) compared to healthy controls, with the greatest reductions observed in non-AD neurodegenerative diseases. Strikingly, combined measurement of plasma TIA-1 and glial fibrillary acidic protein (GFAP) improved differentiation of AD subtypes, particularly distinguishing rpAD from non-rpAD cases. Plasma TIA-1 levels correlated with key biomarkers of neurodegeneration (p-Tau, Aβ42, NFL) and cognitive decline, especially in early AD (MCI-AD). Notably, plasma TIA-1 mirrored the discriminatory patterns of CSF t-Tau and p-Tau, distinguishing non-AD neurodegenerative diseases from specifically rpAD subtype, indicating that plasma TIA-1 captures the same underlying pathophysiological processes as the “gold standard” CSF markers. Conclusions: Plasma TIA-1 is a promising biomarker candidate for neurodegenerative diseases, with alterations that reflect disease presence and severity. In this pilot cohort, its combination with GFAP noticeably improved discrimination between AD subtypes, supporting its potential added value in composite biomarker approaches. Given its accessibility, TIA-1 is a strong candidate for further evaluation as part of future blood-based biomarker panels, although it’s clinical utility still needs confirmation in larger, independent studies.

Rapidly progressive Alzheimer’s disease (rpAD) is a rare subtype with rapid decline, but its molecular underpinnings remain poorly defined. Here, brain-derived tau oligomers (TauO) were systematically compared across nondemented controls, slowly progressive AD (spAD), and rpAD to test whether subtype-specific TauO signatures align with clinical aggressiveness. TauO were immunoprecipitated from frontal cortex using T22 antibody and characterized by Western blotting, transmission electron microscopy, label-free quantitative proteomics, and SH-SY5Y toxicity assays, complemented by longitudinal analysis of tau phosphorylation in inoculated 3xTg AD mice. T22-positive high-molecular-weight TauO were successfully enriched from all groups, where rpAD TauO exhibited compact, densely packed oligomers under TEM and the highest phosphorylation at pS396 and pS422, exceeding both spAD and controls ( p ≤ 0.0327). In 3xTg mice, pS396 showed an early increase followed by a late decline, consistent with dynamic shifts in tau solubility during disease evolution. Brain-derived TauO from spAD and rpAD, but not recombinant tau monomers or control-derived TauO, significantly reduced SH-SY5Y cell viability. Proteomic profiling identified 2388 TauO-associated proteins, including a shared 556-protein core and a striking expansion of rpAD-unique interactors ( n = 1101). In controls and spAD, the core TauO interactome was enriched for translation, proteostasis, mitochondrial respiration, and vesicle-trafficking pathways, whereas these modules were absent in rpAD. Instead, rpAD TauO showed selective enrichment of aldehyde detoxification, amino-acid and carbon metabolism, and actin-regulatory modules, alongside increased association of SERPINA1, ALDH9A1, MAPRE3, DPYSL2, DPYSL3, and NFASC and reduced coupling to mitochondrial (MRPL17) and complement (C9) components. These convergent structural, post-translational, toxic, and interactome changes indicate that rpAD is defined by a biochemically distinct TauO species embedded in a metabolic and cytoskeleton-focused network, providing a mechanistic framework for its aggressive clinical course and a basis for subtype-specific biomarker and therapeutic strategies.

Neurodegenerative diseases, including Alzheimer’s disease (AD) and prion disorders, have historically been studied from a neuron-centric perspective. However, growing evidence highlights glial cells – particularly microglia and astrocytes – as central mediators of disease initiation and progression. Glia maintain central nervous system homeostasis through waste clearance, synaptic regulation, metabolic support, and blood–brain barrier maintenance. In pathological contexts, glial populations undergo morphological and functional changes, commonly termed reactive gliosis, which can be either protective or detrimental depending on the disease stage. In AD, microglial dysfunction impairs amyloid clearance, promotes chronic cytokine release, and contributes to synaptic loss, while reactive astrocytes exacerbate glutamate excitotoxicity and metabolic dysregulation. Similarly, prion diseases demonstrate that glial cells mediate neurotoxicity and pathogen propagation, with astrocytes showing transcriptomic alterations preceding neuronal demise and microglial ablation paradoxically accelerating disease. Shared pathomechanisms between AD and prion diseases include mitochondrial dysfunction, inflammasome activation, cytokine network dysregulation, and impaired phagocytosis, with the NLRP3 inflammasome emerging as a key therapeutic target. Recent advances in single-cell transcriptomics and spatial proteomics are elucidating the molecular heterogeneity of reactive glia, paving the way for precision medicine approaches. Given the challenges of directly targeting misfolded proteins, glia-focused therapies – ranging from anti-inflammatory agents to gene therapy – represent a promising avenue. This chapter reviews the multifaceted roles of glial cells in neurodegeneration, emphasizing how chronic activation, impaired signaling, and genetic susceptibility convert protective functions into drivers of neuronal dysfunction, and explores emerging strategies for glia-targeted interventions in AD and prion diseases.

Rapidly progressive Alzheimer's disease (rpAD) is a rare but severe form of Alzheimer's disease characterized by accelerated cognitive decline and limited therapeutic options. Conventional anti–amyloid‐β interventions have shown little success due to poor target specificity, neurotoxicity, and lack of efficacy, underscoring the need for novel therapeutic strategies. This study aimed to identify and prioritize molecular targets associated with rpAD by investigating the protein interactome of amyloid‐β (Aβ ₄₂ ) using integrative computational approaches. Functional enrichment, protein–protein interaction network analysis, and community clustering revealed that rpAD‐specific Aβ ₄₂ interactors were predominantly involved in mitochondrial bioenergetics, redox regulation, and cytoskeletal stability, pathways central to neuronal survival and synaptic function. Molecular docking identified fumarate hydratase, carbonyl reductase 1, and the F‐actin capping protein as high‐affinity interactors of Aβ ₄₂ , linking these proteins to energy failure, oxidative stress, and synaptic dysfunction. Virtual screening of a therapeutic drug library against fumarate hydratase identified several compounds with strong binding affinities, among which quinestrol, estradiol benzoate, norethindrone, tamibarotene, drospirenone, and ketanserin emerged as lead candidates. Pharmacokinetic profiling, including ADMET modeling, confirmed their blood–brain barrier permeability and drug‐likeness, supporting their potential as central nervous system active agents. Together, this work highlights key molecular targets in rpAD and proposes repurposed, pharmacologically diverse compounds with multitarget neuroprotective potential. By utilizing in silico analysis, the study provides a rational framework for target discovery and drug prioritization in rpAD, offering a foundation for future experimental validation and the development of translational research.

Rapidly progressive Alzheimer's disease (rpAD) is a rare but devastating clinical variant characterized by abrupt cognitive decline, yet the molecular features underlying this phenotype remain unknown. Tau oligomers (TauO) are key mediators of tau toxicity, but whether their biochemical properties differ across AD subtypes has not been examined in human brain. We isolated endogenous TauO from frontal cortex of well-characterized control, slowly progressive AD (spAD), and rpAD cases using T22 immunoprecipitation and performed ultrastructural, biochemical, and proteomic characterization. rpAD TauO displayed compact, densely aggregated morphology and exhibited the highest levels of disease-associated phosphorylation (pS396, pS422). Label-free proteomics revealed that control and spAD shared a robust TauO interactome enriched for translation, proteostasis, mitochondrial metabolism, and vesicle trafficking. Strikingly, these modules were absent in rpAD, which instead showed selective enrichment for aldehyde detoxification, amino-acid and carbon metabolism, and actin-regulatory pathways. rpAD TauO demonstrated increased association with SERPINA1, ALDH9A1, MAPRE3, DPYSL2/3, and NFASC, and reduced association with MRPL17 and C9. Functionally, rpAD TauO induced the strongest toxicity in SH-SY5Y cells. Together, these findings indicate that rpAD likely harbors a biochemically distinct TauO species, defining a molecular signature that may underpin its fulminant clinical progression and support the development of subtype-specific therapeutic strategies.

Alzheimer's disease (AD) may display various clinical phenotypes with different disease progressions, such as rapidly progressive Alzheimer's disease (rpAD) type. The reason for clinical heterogeneity is still unknown and not predictable. Here, we subjected frontal cortex‐derived tau seeds from classical AD, rpAD patients and controls to tau real‐time quaking‐induced conversion (RT‐QuIC) assay analysis and examined biochemical properties, toxicity, and the morphology of tau fibrils generated during the RT‐QuIC applying a cell‐based assay and transmission electron microscopy (TEM). We observed seeding activity of misfolded tau protein in AD patients, which was significantly higher than in control cases. Additionally, the RT‐QuIC signal response revealed differences between AD cases with a classical clinical phenotype and those with a rapidly progressive course of the disease (rpAD). The RT‐QuIC reaction seeded with brain from rpAD exhibited a shorter lag phase, higher area under the curve and a higher seeding end point dilution compared to classical AD, independent from the Braak stage. The cellular toxicity of thioflavin T‐positive RT‐QuIC products from rpAD‐seeded reactions was higher compared to those seeded by classical AD and controls. Morphological characterization of brain tissue‐seeded RT‐QuIC end‐products via TEM showed that tau fibrils derived from rpAD seeded reactions revealed subtly different morphologies compared to classical AD. The study provides evidence for the existence of different tau assemblies in AD with different progression rates. As an alternative explanation, differences in the amounts of misfolded seed or the presence of other co‐factors might influence the seeding activity of tau in AD and rpAD patients.

Synucleins α, β, and γ are inherently disordered proteins that play essential roles in neuronal physiology and are increasingly recognized as key players in neurodegenerative disease mechanisms. The molecular basis of synucleinopathies, including Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy, is the pathological aggregation and misfolding of synucleins. However, the biological significance of the diverse synuclein proteoforms that result from alternative splicing, extensive post-translational modifications, and conformational heterogeneity is still not fully understood. This review systematically incorporates current knowledge of the structural and functional diversity of synuclein proteoforms, highlighting their molecular interactions and aggregation pathways. We investigate the regulatory effects of β and γ-synucleins (β-syn and γ-syn), which have different physiological functions and clinical applications in addition to influencing α-synuclein (α-syn) aggregation. In addition to synucleins' involvement in the central nervous system, recent findings show their role in immune regulation and functions in peripheral tissues, highlighting their systemic relevance. Controversial aspects, such as the mechanisms of prion-like propagation, proteoform-specific toxicity, and differential cellular vulnerability, are thoroughly analyzed. Synuclein proteoforms have been thoroughly characterized due to developments in molecular imaging and proteomic techniques, opening the door for targeted treatment approaches. Developing novel treatments for mitigating the progression of synucleinopathies and enhancing patient outcomes requires an understanding of the complex biology of synuclein proteoforms. The goal of this study is to present a thorough framework that connects translational research and molecular neurobiology in disorders related to synuclein.

Alzheimer’s disease (AD) is presented as multiple clinical variants depending upon the rate of progression and familial background; however, the exact molecular mechanisms associated with these subtypes and their treatments are yet to be understood. The current study is based on a global proteome analysis of brain samples from patients ( n = 38) with rapidly progressive AD (rpAD—survival time < 3 years), sporadic AD (spAD—survival time of 8–10 years), and healthy controls. Proteome analysis revealed a differential regulation of 79 proteins and highlighted the dysregulation of mitochondrial machinery and glucose metabolism in rpAD. Dihydrolipoamide dehydrogenase (DLDH), a mitochondrial oxidoreductase, showed a significant reduction and delocalization in rpAD. In vitro analysis revealed a potential role of DLDH in the aggregation of amyloid beta. Rapid progression in AD may be influenced by the energy homeostasis and redox dysfunction linked with the DLDH.