The clinical diagnosis of synucleinopathies, including Parkinson’s disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA), is challenging, especially at an early disease ...stage, due to the heterogeneous and often non-specific clinical manifestations. The discovery of reliable specific markers for synucleinopathies would consequently be of great aid to the diagnosis and management of these disorders. Real-Time Quaking-Induced Conversion (RT-QuIC) is an ultrasensitive technique that has been previously used to detect self-templating amyloidogenic proteins in the cerebrospinal fluid (CSF) and other biospecimens in prion disease and synucleinopathies. Using a wild-type recombinant α-synuclein as a substrate, we applied RT-QuIC to a large cohort of 439 CSF samples from clinically well-characterized, or post-mortem verified patients with parkinsonism or dementia. Of significance, we also studied patients with isolated REM sleep behavior disorder (iRBD) (
n
= 18) and pure autonomic failure (PAF) (
n
= 28), representing clinical syndromes that are often caused by a synucleinopathy, and may precede the appearance of parkinsonism or cognitive decline. The results show that our RT-QuIC assay can accurately detect α-synuclein seeding activity across the spectrum of Lewy Body (LB)-related disorders (LBD), including DLB, PD, iRBD, and PAF, with an overall sensitivity of 95.3%. In contrast, all but two patients with MSA showed no α-synuclein seeding activity in the applied experimental setting. The analysis of the fluorescence response reflecting the amount of α-synuclein seeds revealed no significant differences between the clinical syndromes associated with LB pathology. Finally, the assay demonstrated 98% specificity in a neuropathological cohort of 101 cases lacking LB pathology. In conclusion, α-synuclein RT-QuIC provides an accurate marker of synucleinopathies linked to LB pathology and may have a pivotal role in the early discrimination and management of affected patients. The finding of no α-synuclein seeding activity in MSA seems to support the current view that MSA and LBD are associated with different conformational strains of α-synuclein.
The current classification of sporadic Creutzfeldt–Jakob disease (sCJD) includes six major clinicopathological subtypes defined by the physicochemical properties of the protease-resistant core of the ...pathologic prion protein (PrP
Sc
), defining two major PrP
Sc
types (i.e., 1 and 2), and the methionine (M)/valine (V) polymorphic codon 129 of the prion protein gene (
PRNP
). How these sCJD subtypes relate to the well-documented phenotypic heterogeneity of genetic CJD (gCJD) is not fully understood. We analyzed molecular and phenotypic features in 208 individuals affected by gCJD, carrying 17 different mutations, and compared them with those of a large series of sCJD cases. We identified six major groups of gCJD based on the combination PrP
Sc
type and codon 129 genotype on
PRNP
mutated allele, each showing distinctive histopathological characteristics, irrespectively of the
PRNP
associated mutation. Five gCJD groups, named M1, M2C, M2T, V1, and V2, largely reproduced those previously described in sCJD subtypes. The sixth group shared phenotypic traits with the V2 group and was only detected in patients carrying the E200K-129M haplotype in association with a PrP
Sc
type of intermediate size (“i”) between type 1 and type 2. Additional mutation-specific effects involved the pattern of PrP deposition (e.g., a “thickened” synaptic pattern in E200K carriers, cerebellar “stripe-like linear granular deposits” in those with insertion mutations, and intraneuronal globular dots in E200K-V2 or -M”i”). A few isolated cases linked to rare
PRNP
haplotypes (e.g., T183A-129M), showed atypical phenotypic features, which prevented their classification into the six major groups. The phenotypic variability of gCJD is mostly consistent with that previously found in sCJD. As in sCJD, the codon 129 genotype and physicochemical properties of PrP
Sc
significantly correlated with the phenotypic variability of gCJD. The most common mutations linked to CJD appear to have a variable and overall less significant effect on the disease phenotype, but they significantly influence disease susceptibility often in a strain-specific manner. The criteria currently used for sCJD subtypes can be expanded and adapted to gCJD to provide an updated classification of the disease with a molecular basis.
Prion real-time quaking-induced conversion (RT-QuIC) is emerging as the most potent assay for the in vivo diagnosis of Creutzfeldt–Jakob disease (CJD), but its full application, especially as a ...screening test, is limited by suboptimal substrate availability, reagent costs, and incomplete assay standardization. Therefore, the search for the most informative cerebrospinal fluid (CSF) surrogate biomarker is still of primary importance. We compared the diagnostic accuracy of CSF protein 14-3-3, measured with both western blot (WB) and enzyme-linked immunosorbent assay (ELISA), total (t)-tau and neurofilament light chain protein (NfL) alone or in combination with RT-QuIC in 212 subjects with rapidly progressive dementia in which we reached a highly probable clinical diagnosis at follow-up or a definite neuropathological diagnosis. T-tau performed best as surrogate CSF biomarker for the diagnosis of CJD (91.3% sensitivity and 78.9% specificity). The 14-3-3 ELISA assay demonstrated a slightly higher diagnostic value compared to the WB analysis (76.9% vs. 72.2%), but both methods performed worse than the t-tau assay. NfL was the most sensitive biomarker for all sCJD subtypes (> 95%), including those with low values of t-tau or 14-3-3, but showed the lowest specificity (43.1%). When ELISA-based biomarkers were adopted as screening tests followed by RT-QuIC, t-tau correctly excluded a higher number of non-CJD cases compared to NfL and 14-3-3 ELISA. Our study showed that among the CSF surrogate biomarkers of potential application for the clinical diagnosis of CJD, t-tau performs best either alone or as screening test followed by RT-QuIC as a second-level confirmatory test.
In neurodegenerative dementias (NDs) such as prion disease, Alzheimer's disease (AD), and frontotemporal lobar degeneration (FTLD), protein misfolding leads to the tissue deposition of protein ...aggregates which, in turn, trigger neuroinflammation and neurodegeneration. Cerebrospinal fluid (CSF) biomarkers have the potential to reflect different aspects of these phenomena across distinct clinicopathological subtypes and disease stages.
We investigated CSF glial markers, namely chitotriosidase 1 (CHIT1), chitinase-3-like protein 1 (YKL-40) and glial fibrillary acidic protein (GFAP) in prion disease subtypes (n = 101), AD (n = 40), clinicopathological subgroups of FTLD (n = 72), and controls (n = 40) using validated, commercially available ELISA assays. We explored glial biomarker levels' associations with disease variables and neurodegenerative CSF biomarkers and evaluated their diagnostic accuracy. The genotype of the CHIT1 rs3831317 polymorphic site was also analyzed.
Each ND group showed increased levels of CHIT1, YKL-40, and GFAP compared to controls with a difference between prion disease and AD or FTLD limited to YKL-40, which showed higher values in the former group. CHIT1 levels were reduced in both heterozygotes and homozygotes for the CHIT1 24-bp duplication (rs3831317) in FTLD and controls, but this effect was less significant in AD and prion disease. After stratification according to molecular subgroups, we demonstrated (i) an upregulation of all glial markers in Creutzfeldt-Jakob disease VV2 compared to other disease subtypes, (ii) a difference in CHIT1 levels between FTLD with TAU and TDP43 pathology, and (iii) a marked increase of YKL-40 in FTLD with amyotrophic lateral sclerosis (ALS) in comparison with FTLD without ALS. In prion disease, glial markers correlated with disease stage and were already elevated in one pre-symptomatic case of Gerstmann-Sträussler-Scheinker disease. Regarding the diagnostic value, YKL-40 was the only glial marker that showed a moderate accuracy in the distinction between controls and NDs.
NDs share a CSF profile characterized by increased levels of CSF CHIT1, YKL-40, and GFAP, which likely reflects a common neuroinflammatory response to protein misfolding and aggregation. CSF glial markers of neuroinflammation demonstrate limited diagnostic value but have some potential for monitoring the clinical and, possibly, preclinical phases of NDs.
Increasing evidence supports the use of plasma biomarkers of neurodegeneration and neuroinflammation to screen and diagnose patients with dementia. However, confirmatory studies are required to ...demonstrate their usefulness in the clinical setting.
We evaluated plasma and cerebrospinal fluid (CSF) samples from consecutive patients with frontotemporal dementia (FTD) (n = 59), progressive supranuclear palsy (PSP) (n = 31), corticobasal syndrome (CBS) (n = 29), dementia with Lewy bodies (DLB) (n = 49), Alzheimer disease (AD) (n = 97), and suspected non-AD physiopathology (n = 51), as well as plasma samples from 60 healthy controls (HC). We measured neurofilament light chain (NfL), phospho-tau181 (p-tau181), and glial fibrillary acid protein (GFAP) using Simoa (all plasma biomarkers and CSF GFAP), CLEIA (CSF p-tau181), and ELISA (CSF NfL) assays. Additionally, we stratified patients according to the A/T/N classification scheme and the CSF α-synuclein real-time quaking-induced conversion assay (RT-QuIC) results.
We found good correlations between CSF and plasma biomarkers for NfL (rho = 0.668, p < 0.001) and p-tau181 (rho = 0.619, p < 0.001). Plasma NfL was significantly higher in disease groups than in HC and showed a greater increase in FTD than in AD 44.9 (28.1-68.6) vs. 21.9 (17.0-27.9) pg/ml, p < 0.001. Conversely, plasma p-tau181 and GFAP levels were significantly higher in AD than in FTD 3.2 (2.4-4.3) vs. 1.1 (0.7-1.6) pg/ml, p < 0.001; 404.7 (279.7-503.0) vs. 198.2 (143.9-316.8) pg/ml, p < 0.001. GFAP also allowed discriminating disease groups from HC. In the distinction between FTD and AD, plasma p-tau181 showed better accuracy (AUC 0.964) than NfL (AUC 0.791) and GFAP (AUC 0.818). In DLB and CBS, CSF amyloid positive (A+) subjects had higher plasma p-tau181 and GFAP levels than A- individuals. CSF RT-QuIC showed positive α-synuclein seeding activity in 96% DLB and 15% AD patients with no differences in plasma biomarker levels in those stratified by RT-QuIC result.
In a single-center clinical cohort, we confirm the high diagnostic value of plasma p-tau181 for distinguishing FTD from AD and plasma NfL for discriminating degenerative dementias from HC. Plasma GFAP alone differentiates AD from FTD and neurodegenerative dementias from HC but with lower accuracy than p-tau181 and NfL. In CBS and DLB, plasma p-tau181 and GFAP levels are significantly influenced by beta-amyloid pathology.
The diagnostic and prognostic value of plasma glial fibrillary acidic protein (pl-GFAP) in sporadic Creutzfeldt-Jakob disease (sCJD) has never been assessed in the clinical setting of rapidly ...progressive dementia (RPD). Using commercially available immunoassays, we assayed the plasma levels of GFAP, tau (pl-tau), and neurofilament light chain (pl-NfL) and the CSF total tau (t-tau), 14-3-3, NfL, phospho-tau181 (p-tau), and amyloid-beta isoforms 42 (Aβ
) and 40 (Aβ
) in sCJD (
= 132) and non-prion RPD (np-RPD) (
= 94) patients, and healthy controls (HC) (
= 54). We also measured the CSF GFAP in 67 sCJD patients. Pl-GFAP was significantly elevated in the sCJD compared to the np-RPD and HC groups and affected by the sCJD subtype. Its diagnostic accuracy (area under the curve (AUC) 0.760) in discriminating sCJD from np-RPD was higher than the plasma and CSF NfL (AUCs of 0.596 and 0.663) but inferior to the 14-3-3, t-tau, and pl-tau (AUCs of 0.875, 0.918, and 0.805). Pl-GFAP showed no association with sCJD survival after adjusting for known prognostic factors. Additionally, pl-GFAP levels were associated with 14-3-3, pl-tau, and pl-NfL but not with CSF GFAP, Aβ
/Aβ
, and p-tau. The diagnostic and prognostic value of pl-GFAP is inferior to established neurodegeneration biomarkers. Nonetheless, pl-GFAP noninvasively detects neuroinflammation and neurodegeneration in sCJD, warranting potential applications in disease monitoring.
The clinicopathological heterogeneity in Lewy-body diseases (LBD) highlights the need for pathology-driven biomarkers in-vivo. Misfolded alpha-synuclein (α-Syn) is a lead candidate based on its ...crucial role in disease pathophysiology. Real-time quaking-induced conversion (RT-QuIC) analysis of CSF has recently shown high sensitivity and specificity for the detection of misfolded α-Syn in patients with Parkinson's disease (PD) and dementia with Lewy bodies (DLB). In this study we performed the CSF RT-QuIC assay in 236 PD and 49 DLB patients enriched for different genetic forms with mutations in GBA, parkin, PINK1, DJ1, and LRRK2. A subgroup of 100 PD patients was also analysed longitudinally. We correlated kinetic seeding parameters of RT-QuIC with genetic status and CSF protein levels of molecular pathways linked to α-Syn proteostasis. Overall, 85% of PD and 86% of DLB patients showed positive RT-QuIC α-Syn seeding activity. Seeding profiles were significantly associated with mutation status across the spectrum of genetic LBD. In PD patients, we detected positive α-Syn seeding in 93% of patients carrying severe GBA mutations, in 78% with LRRK2 mutations, in 59% carrying heterozygous mutations in recessive genes, and in none of those with bi-allelic mutations in recessive genes. Among PD patients, those with severe GBA mutations showed the highest seeding activity based on RT-QuIC kinetic parameters and the highest proportion of samples with 4 out of 4 positive replicates. In DLB patients, 100% with GBA mutations showed positive α-Syn seeding compared to 79% of wildtype DLB. Moreover, we found an association between α-Syn seeding activity and reduced CSF levels of proteins linked to α-Syn proteostasis, specifically lysosome-associated membrane glycoprotein 2 and neurosecretory protein VGF.These findings highlight the value of α-Syn seeding activity as an in-vivo marker of Lewy-body pathology and support its use for patient stratification in clinical trials targeting α-Syn.
Neurofilament light chain protein (NfL) is currently the most accurate cerebrospinal fluid (CSF) biomarker in amyotrophic lateral sclerosis (ALS) in terms of both diagnostic and prognostic value, but ...the mechanism underlying its increase is still a matter of debate. Similarly, emerging CSF biomarkers of neurodegeneration and neuroinflammation showed promising results, although further studies are needed to clarify their clinical and pathophysiological roles. In the present study we compared the diagnostic accuracy of CSF NfL, phosphorylated (p)-tau/total (t)-tau ratio, chitinase-3-like protein 1 (YKL-40) and chitotriosidase 1 (CHIT1), in healthy controls (
n
= 43) and subjects with ALS (
n
= 80) or ALS mimics (
n
= 46). In ALS cases, we also investigated the association between biomarker levels and clinical variables, the extent of upper motor neuron (UMN) and lower motor neuron (LMN) degeneration, and denervation activity through electromyography (EMG). ALS patients showed higher levels of CSF NfL, YKL-40, CHIT1, and lower values of p-tau/t-tau ratio compared to both controls and ALS mimics. Among all biomarkers, NfL yielded the highest diagnostic performance (> 90% sensitivity and specificity) and was the best predictor of disease progression rate and survival in ALS. NfL levels showed a significant correlation with the extent of LMN involvement, whereas YKL-40 levels increased together with the number of areas showing both UMN and LMN damage. EMG denervation activity did not correlate with any CSF biomarker change. These findings confirm the highest value of NfL among currently available CSF biomarkers for the diagnostic and prognostic assessment of ALS and contribute to the understanding of the pathophysiological and electrophysiological correlates of biomarker changes.
Exploitation of the remarkable kinetic inertness and ability of chiral aggregates built with opposite charged porphyrins to self-replicate leads to a system able to cycle between a chiral and an ...“achiral” state.
Background The levels of synaptic markers synaptosomal-associated protein 25 (SNAP-25) and neurogranin (Ng) have been shown to increase early in the cerebrospinal fluid (CSF) of patients with ...Creutzfeldt-Jakob disease (CJD) and to have prognostic potential. However, no validation studies assessed these biomarkers' diagnostic and prognostic value in a large clinical setting cohort of rapidly progressive dementia. Methods In this retrospective study, using commercially available immunoassays, we measured the levels of SNAP-25, Ng, 14-3-3, total-tau (t-tau), neurofilament light chain (NfL), and phospho-tau181 (p-tau) in CSF samples from consecutive patients with CJD (n = 220) or non-prion rapidly progressive dementia (np-RPD) (n = 213). We evaluated and compared the diagnostic accuracy of each CSF biomarker and biomarker combination by receiver operating characteristics curve (ROC) analyses, studied SNAP-25 and Ng CSF concentrations distribution across CJD subtypes, and estimated their association with survival using multivariable Cox regression analyses. Results CSF SNAP-25 and Ng levels were higher in CJD than in np-RPD (SNAP-25: 582, 95% CI 240-1250 vs. 115, 95% CI 78-157 pg/ml, p < 0.0001; Ng: 841, 95% CI 411-1473 vs. 390, 95% CI 260-766 pg/ml, p < 0.001). SNAP-25 diagnostic accuracy (AUC 0.902, 95% CI 0.873-0.931) exceeded that of 14-3-3 (AUC 0.853, 95% CI 0.816-0.889), t-tau (AUC 0.878, 95% CI 0.845-0.901), and the t-tau/p-tau ratio (AUC 0.884, 95% CI 0.851-0.916). In contrast, Ng performed worse (AUC 0.697, 95% CI 0.626-0.767) than all other surrogate biomarkers, except for NfL (AUC 0.649, 95% CI 0.593-0.705). SNAP-25 maintained a relatively high diagnostic value even for atypical CJD subtypes (AUC 0.792, 95% CI 0.729-0.854). In Cox regression analyses, SNAP-25 levels were significantly associated with survival in CJD (hazard ratio HR 1.71 95% CI 1.40-2.09). Conversely, Ng was associated with survival only in the most rapidly progressive CJD subtypes (sCJD MM(V)1 and gCJD M1) (HR 1.81 95% CI 1.21-2.93). Conclusions In the clinical setting, CSF SNAP-25 is a viable alternative to t-tau, 14-3-3, and the t-tau/p-tau ratio in discriminating the CJD subtypes from other RPDs. Additionally, SNAP-25 and, to a lesser extent, Ng predict survival in CJD, showing prognostic power in the range of CSF t-tau/14-3-3 and NfL, respectively. Keywords: Cognitive Disorders, Dementia, Prion disease, SNAP-25, Neurogranin, Tau, Neurofilament, Synapses, Creutzfeldt-Jakob
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