Over the past decades, growing experimental and observational evidence has suggested that Aβ and pTau, the hallmarks of Alzheimer’s disease (AD), may spread through the nervous system via a prion-like mechanism. Here, we investigated the transmissibility of Aβ and pTau by inoculating bank voles, a wild-type rodent highly susceptible to prion diseases, with brain homogenates from four sporadic and five familial AD-affected patients. We observed that (i) neo-formed Aβ deposits and pTau inclusions were induced in recipient vole brains; (ii) Aβ pathology appeared to follow a specific neurotropic distribution; (iii) Aβ proteinopathy propagated through vole-to-vole inoculation. Our findings provide the first experimental evidence that human Aβ seeds are transmissible to a wild-type rodent model, further supporting the prion-like nature of Aβ. These results strongly support recent studies suggesting iatrogenic Aβ transmission, underscoring the need to evaluate the impact of Aβ seed exposure on human health.

Background Parkinson’s disease (PD) is a complex neurodegenerative disorder characterized by motor and non-motor symptoms. Early diagnosis remains challenging due to the lack of reliable, non-invasive biomarkers. Here, we explored the potential of tear fluid (TF) as a diagnostic source by profiling its microRNA (miRNA) content. Methods The study included a discovery (8 PD, 7 healthy controls (HC)) and a replication cohort (9 PD, 9 HC). miRNA expression was assessed using TaqMan Human MicroRNA arrays. Independent in-silico validation was conducted using a qPCR-based miRNA array dataset comprising pooled cDNA samples from controls (n = 10) and PD patients (n = 29). The relationship between microRNA expression and composite clinical scores in PD patients was explored. Target gene prediction, pathway enrichment, and interaction network analyses were performed. Results The t-RNA-derived miR-1274b was consistently upregulated in the TF of PD patients across the discovery and replication cohorts, with additional in-silico support from the independent dataset. Increased expression was particularly evident in a PD subgroup characterized by combined non-motor autonomic symptoms. Predicted target genes were associated with neurodegeneration and cellular dysfunction. Over-representation analysis highlighted pathways related to negative regulation of synaptic transmission, while network analysis revealed interactions between miRNA targets and key PD-related genes, supporting a potential role in disease mechanisms. Conclusions Our findings identify miR-1274b as a TF-based miRNA associated with PD, supporting its potential as a non-invasive biomarker. Further studies with larger cohorts and other neurodegenerative diseases are needed to validate these results and explore their clinical applicability.

Tofersen is a gene-targeted therapy for superoxide dismutase 1 (SOD1)-associated amyotrophic lateral sclerosis (ALS), but neurofilament light chain (NfL) may not fully capture the biological response to treatment. We performed a multicentre retrospective longitudinal study including 24 patients with SOD1-ALS treated with intrathecal tofersen at four Italian referral centres between 2022 and 2025. Cerebrospinal fluid (CSF) and serum biomarkers were assessed at baseline, month 3, month 6, and last available administration using single-molecule array assays to quantify NfL, glial fibrillary acidic protein (GFAP), ubiquitin C-terminal hydrolase L1 (UCHL-1), and total Tau. NfL decreased after treatment initiation in both CSF and serum, providing the clearest pharmacodynamic signal. In contrast, CSF GFAP increased progressively over follow-up, while CSF total Tau and UCHL-1 rose mainly at later timepoints; serum GFAP, total Tau, and UCHL-1 also showed increases during follow-up. ALS Functional Rating Scale-Revised trajectories were broadly stable, whereas disease progression rate was lower at last follow-up than at baseline. Greater reductions in CSF NfL were observed in pathogenic versus uncertain SOD1 variants, and early serum NfL and UCHL-1 changes were associated with longer-term changes in disease progression. These findings suggest that longitudinal multi-analyte profiling may refine biological response stratification beyond NfL alone in tofersen-treated SOD1-ALS.

INTRODUCTION:Seed amplification assays (SAAs) have shown promising results in detecting misfolded transactive response (TAR) DNA-binding protein 43 (TDP-43) in cerebrospinal fluid (CSF) of genetic frontotemporal dementia (FTD). To date, the use of SAA has yet to be evaluated in presymptomatic individuals. METHODS:Thirty patients carrying GRN or C9orf72 mutations, 2 microtubule-associated protein tau (MAPT) carriers, 14 presymptomatic subjects, and 27 controls underwent CSF collection. We used SAA for detecting misfolded TDP-43 (TDP-43_SAA) and single molecule array (SIMOA) technology for neurofilament light chain (NfL) dosage. RESULTS:TDP-43 seeding activity was detected in 67% of TDP-43-linked symptomatic patients, with a specificity of 93%. Almost half of presymptomatic subjects tested positive, mostly GRN carriers. Interestingly, among TDP-43_SAA positive presymptomatic individuals, two GRN carriers underwent phenoconversion. DISCUSSION:TDP-43_SAA can also detect misfolded TDP-43 in the CSF of presymptomatic individuals. A possible link exists between positive TDP-43_SAA and conversion to the symptomatic phase. HIGHLIGHTS:Seed amplification assay of transactive response (TAR) DNA-binding protein 43 (TDP-43_SAA) can detect misfolded TDP-43 in the cerebrospinal fluid (CSF) of patients with genetic frontotemporal dementia (FTD), linked to GRN and C9orf72 mutations. TDP-43_SAA can detect misfolded TDP-43 also in the CSF of presymptomatic individuals. In both groups, most TDP-43_SAA positive cases were carriers of GRN mutation. Two GRN carriers that resulted TDP-43_SAA positive converted to the symptomatic phase of the disease.

Alzheimer's disease, the leading cause of dementia globally, represents an unresolved clinical challenge due to its complex pathogenesis and the absence of effective treatments. Considering the multifactorial etiology of the disease, mainly characterized by the accumulation of amyloid (3 plaques and neurofibrillary tangles of tau protein, we discuss the A673V mutation in the gene coding for the amyloid precursor protein, which is associated with the familial form of Alzheimer's disease in a homozygous state. The mutation offers new insights into the molecular mechanisms of the disease, particularly regarding the contrasting roles of the A2V and A2T mutations in amyloid (3 peptide aggregation and toxicity. This review aims to describe relevant studies on A2V-mutated variants of the amyloid (3 peptide, revealing a protective effect against amyloid-(3 and tau pathology. Notably, special attention is given to the development of the peptide A(31-6A2V(D), which shows significant neuroprotective activity through inhibition of the assembly of amyloid (3 into amyloid fibrils. The therapeutic potential of this peptide emerges from its ability to reduce amyloid (3-induced toxicity, with promising results from studies in human neuroblastoma cells and transgenic animal models.

In recent years, the seed amplification assay (SAA) has enabled the identification of pathological TDP-43 in the cerebrospinal fluid (CSF) and olfactory mucosa (OM) of patients with genetic forms of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). Here, we investigated the seeding activity of TDP-43 in OM samples collected from patients with sporadic ALS. OM samples were collected from patients with (a) sporadic motor neuron diseases (MND), including spinal ALS (n = 35), bulbar ALS (n = 18), primary lateral sclerosis (n = 10), and facial onset sensory and motor neuronopathy (n = 2); (b) genetic MND, including carriers of C9orf72exp (n = 6), TARDBP (n = 4), SQSTM1 (n = 3), C9orf72exp + SQSTM1 (n = 1), OPTN (n = 1), GLE1 (n = 1), FUS (n = 1) and SOD1 (n = 4) mutations; (c) other neurodegenerative disorders (OND), including Alzheimer’s disease (n = 3), dementia with Lewy bodies (n = 8) and multiple system atrophy (n = 6); and (d) control subjects (n = 22). All samples were subjected to SAA analysis for TDP-43 (TDP-43_SAA). Plasmatic levels of TDP-43 and neurofilament-light chain (NfL) were also assessed in a selected number of patients. TDP-43_SAA was positive in 29/65 patients with sporadic MND, 9/21 patients with genetic MND, 6/17 OND patients and 3/22 controls. Surprisingly, one presymptomatic individual also tested positive. As expected, OM of genetic non-TDP-43-related MND tested negative. Interestingly, fluorescence values from non-MND samples that tested positive were consistently and significantly lower than those obtained with sporadic and genetic MND. Furthermore, among TDP-43-positive samples, the lag phase observed in MND patients was significantly longer than that in non-MND patients. Plasma TDP-43 levels were significantly higher in sporadic MND patients compared to controls and decreased as the disease progressed. Similarly, plasma NfL levels were higher in both sporadic and genetic MND patients and positively correlated with disease progression rate (ΔFS). No significant correlations were detected between TDP-43_SAA findings and the biological, clinical, or neuropsychological parameters considered. The OM of a subset of patients with sporadic MND can trigger seeding activity for TDP-43, as previously observed in genetic MND. Thus, TDP-43_SAA analysis of OM can improve the clinical characterization of ALS across different phenotypes and enhance our understanding of these diseases. Finally, plasma TDP-43 could serve as a potential biomarker for monitoring disease progression. However, further research is needed to confirm and expand these findings.

The approval of new disease-modifying therapies by the U.S. Food and Drug Administration and the European Medicine Agency makes it necessary to optimize non-invasive and cost-effective tools for the identification of subjects at-risk of developing Alzheimer’s Disease (AD). Plasma biomarkers are excellent candidates. However, their ability to reflect the cerebrospinal fluid (CSF) profile - that remains to date the gold standard for the biochemical diagnosis of AD - needs to be confirmed and validated before their implementation in clinical practice. The aims of this study are to analyse the correlation between CSF and plasma Aβ40, Aβ42, Aβ42/Aβ40 and pTau181, and to assess the diagnostic performance of plasma biomarkers in a cohort of subjects affected by Mild Cognitive Impairment (MCI). The study was performed on 306 subjects affected by MCI, enrolled in the context of the Italian Interceptor Project. Aβ40, Aβ42 and pTau181 were analysed in plasma and CSF, and pTau217 was measured in plasma. The fully automated chemiluminescence enzyme immunoassay and the Lumipulse® G600II (Fujirebio) instrument were used for all measurements. We analysed the correlations between CSF and plasma biomarkers and the differences of plasma biomarker concentrations after grouping MCI cases according to AT classification of CSF AD biomarker profiles. We found statistically significant positive correlations between CSF and plasma Aβ42, Aβ42/Aβ40 ratio and pTau181. All the biomarkers, except Aβ40, showed differences in A+ vs. A-, A+T+ vs. A-T- and A+T- vs. A-T- patients. Moreover, Aβ42 and Aβ42/Aβ40 plasma levels were lower in A+T- compared to A-T- and A-T+ groups, and pTau181 and pTau217 plasma levels were higher in A+T+ compared to A+T-. Aβ42/Aβ40 and pTau217 showed a robust performance in distinguishing A+ from A- (AUC = 0.857 and 0.862, respectively) and A+T+ from A-T- (AUC = 0.866 and 0.911) subjects. Our results suggest that plasma biomarkers, and especially Aβ42/Aβ40 ratio and pTau217, are promising candidates for the early detection of AD pathology.

The accumulation of protein aggregates defines distinct, yet overlapping pathologies such as Alzheimer's disease (AD), dementia with Lewy bodies (DLB), and frontotemporal dementia (FTD). In this study, we investigated ATG5, UBQLN2, ULK1, and LC3 concentrations in 66 brain specimens and 120 plasma samples from AD, DLB, FTD, and control subjects (CTRL). Protein concentration was measured with ELISA kits in temporal, frontal, and occipital cortex specimens of 32 AD, 10 DLB, 10 FTD, and 14 CTRL, and in plasma samples of 30 AD, 30 DLB, 30 FTD, and 30 CTRL. We found alterations in ATG5, UBQLN2, ULK1, and LC3 levels in patients; ATG5 and UBQLN2 levels were decreased in both brain specimens and plasma samples of patients compared to those of the CTRL, while LC3 levels were increased in the frontal cortex of DLB and FTD patients. In this study, we demonstrate alterations in different steps related to ATG5, UBQLN2, and LC3 autophagy pathways in DLB and FTD patients. Molecular alterations in the autophagic processes could play a role in a shared pathway involved in the pathogenesis of neurodegeneration, supporting the hypothesis of a common molecular mechanism underlying major neurodegenerative dementias and suggesting different potential therapeutic targets in the autophagy pathway for these disorders.

OBJECTIVES:Recently, a subset of patients affected by cerebral amyloid angiopathy (CAA) distinguished by atypical juvenile onset and a hypothesized iatrogenic origin (iatrogenic CAA, iCAA) has emerged. β-Amyloid (Aβ) accumulation evidenced by amyloid PET positivity or CSF Aβ decrease was included in the iCAA diagnostic criteria. Conversely, diagnostic criteria for sporadic CAA (sCAA) do not involve biomarker analysis. The aim of this study was to assess CSF and plasma levels of Aβ and tau in iCAA and sCAA cohorts. METHODS:Patients affected by probable or possible CAA according to established criteria (Boston 2.0) were prospectively recruited at Fondazione IRCCS Carlo Besta and San Gerardo dei Tintori from May 2021 to January 2024. Patients with probable and possible iCAA or sCAA with available plasma and/or CSF samples were included. Clinical and neurologic data were collected, and levels of Aβ40, Aβ42, total tau, and phospho-tau (p-tau) were assessed in CSF and plasma by SiMoA and Lumipulse. RESULTS:21 patients with iCAA (72% male, mean age at symptom onset 50 years [36-74]) and 32 patients with sCAA (44% male, mean age at symptom onset 68 years [52-80]) were identified. Cognitive impairment and cardiovascular risk factors in the sCAA cohort were more common compared with the iCAA cohort. Patients with sCAA and iCAA showed similar CSF levels for Aβ40 (p = 0.5 [sCAA, 95% CI 2,604-4,228; iCAA, 95% CI 1,958-3,736]), Aβ42 (p = 0.7 [sCAA, 95% CI 88-157; iCAA, 95% CI 83-155]), and total tau (p = 0.08 [sCAA, 95% CI 80-134; iCAA, 95% CI 37-99]). Plasma levels of Aβ40 (p = 0.08, 95% CI 181-222), Aβ42 (p = 0.3, 95% CI 6-8), and total tau (p = 0.4, 95% CI 3-6) were not statistically different in patients with sCAA compared with iCAA ones (Aβ40, 95% CI 153-193; Aβ42, 95% CI 6-7 and total tau, 95% CI 2-4). DISCUSSION:Despite presenting with a younger age at onset, fewer cardiovascular risk factors, and lower cognitive impairment, patients with iCAA demonstrated Aβ and tau levels comparable with elderly patients with sCAA, supporting a common molecular paradigm between the 2 CAA forms.

AbstractMethodsThis study assessed data from two cohorts of patients with alpha‐synucleinopathies (University of Brescia and University of Rome Tor‐Vergata cohorts). Consecutive participants with video‐polysomnography‐confirmed iRBD, Parkinson's disease (PD), dementia with Lewy bodies (DLB) and controls underwent neurological, clinical and 123I‐FP‐CIT SPECT imaging assessments. Individuals with iRBD were longitudinally monitored to collect clinical phenoconversion to PD or DLB. The main outcome was to identify whole brain 123 I‐FP‐CIT SPECT measures reflecting monoaminergic deficits in each clinical group as compared to controls.ResultsThe cohort (n = 184) included 45 patients with iRBD, 47 PD, 42 DLB and 50 age‐matched controls. Individuals with iRBD were categorized as RBD‐DAT− (n = 32) and RBD‐DAT+ (n = 13), according to nigrostriatal assessment used in clinical practice. Compared to controls, RBD‐DAT− showed an early involvement of the left insula, which increased in RBD‐DAT+, and was present in patients with Parkinson's disease and dementia with Lewy bodies. Longitudinal cox regression analyses revealed a higher risk of phenoconversion in individuals with iRBD and insular monoaminergic deficits [HR = 3.387; CI 95%: 1.18–10.27].InterpretationIn this study, altered insular monoaminergic binding in iRBD was associated with phenoconversion to DLB or PD. These findings may provide a helpful stratification approach for future pharmacological or non‐pharmacological interventions.

Alzheimer’s disease, the leading cause of dementia globally, represents an unresolved clinical challenge due to its complex pathogenesis and the absence of effective treatments. Considering the multifactorial etiology of the disease, mainly characterized by the accumulation of amyloid β plaques and neurofibrillary tangles of tau protein, we discuss the A673V mutation in the gene coding for the amyloid precursor protein, which is associated with the familial form of Alzheimer’s disease in a homozygous state. The mutation offers new insights into the molecular mechanisms of the disease, particularly regarding the contrasting roles of the A2V and A2T mutations in amyloid β peptide aggregation and toxicity.This review aims to describe relevant studies on A2V-mutated variants of the amyloid β peptide, revealing a protective effect against amyloid-β and tau pathology. Notably, special attention is given to the development of the peptide Aβ1-6A2V(D), which shows significant neuroprotective activity through inhibition of the assembly of amyloid β into amyloid fibrils. The therapeutic potential of this peptide emerges from its ability to reduce amyloid β-induced toxicity, with promising results from studies in human neuroblastoma cells and transgenic animal models.

Alzheimer’s disease (AD), the leading cause of dementia in older adults, is a double proteinopathy characterized by amyloid-β (Aβ) and tau pathology. Despite enormous efforts that have been spent in the last decades to find effective therapies, late pharmacological interventions along the course of the disease, inaccurate clinical methodologies in the enrollment of patients, and inadequate biomarkers for evaluating drug efficacy have not allowed the development of an effective therapeutic strategy. The approaches followed so far for developing drugs or antibodies focused solely on targeting Aβ or tau protein. This paper explores the potential therapeutic capacity of an all-D-isomer synthetic peptide limited to the first six amino acids of the N-terminal sequence of the A2V-mutated Aβ, Aβ1-6A2V(D), that was developed following the observation of a clinical case that provided the background for its development. We first performed an in-depth biochemical characterization documenting the capacity of Aβ1-6A2V(D) to interfere with the aggregation and stability of tau protein. To tackle Aβ1-6A2V(D) in vivo effects against a neurological decline in genetically predisposed or acquired high AD risk mice, we tested its effects in triple transgenic animals harboring human PS1(M146 V), APP(SW), and MAPT(P301L) transgenes and aged wild-type mice exposed to experimental traumatic brain injury (TBI), a recognized risk factor for AD. We found that Aβ1-6A2V(D) treatment in TBI mice improved neurological outcomes and reduced blood markers of axonal damage. Exploiting the C. elegans model as a biosensor of amyloidogenic proteins’ toxicity, we observed a rescue of locomotor defects in nematodes exposed to the brain homogenates from TBI mice treated with Aβ1-6A2V(D) compared to TBI controls. By this integrated approach, we demonstrate that Aβ1-6A2V(D) not only impedes tau aggregation but also favors its degradation by tissue proteases, confirming that this peptide interferes with both Aβ and tau aggregation propensity and proteotoxicity.

Levels of Abeta40, Abeta42 and aggregated Abeta results obtained from plaque count densitometric analysis of ctf and synaptic proteins levels of antibodies against Abeta42 and Abeta1-6