Neurofilaments and progranulin are related to atrophy in frontotemporal lobar degeneration - A transdiagnostic study cross-validating atrophy and fluid biomarkers.

INTRODUCTION: Frontotemporal lobar degeneration (FTLD) encompasses behavioral variant frontotemporal dementia (bvFTD), progressive supranuclear palsy, corticobasal syndrome/degeneration, and primary progressive aphasias (PPAs). We cross-validated fluid biomarkers and neuroimaging. METHODS: Seven fluid biomarkers from cerebrospinal fluid and serum were related to atrophy in 428 participants including these FTLD subtypes, logopenic variant PPA (lvPPA), Alzheimer's disease (AD), and healthy subjects. Atrophy was assessed by structural magnetic resonance imaging and atlas-based volumetry. RESULTS: FTLD subtypes, lvPPA, and AD showed specific profiles for neurofilament light chain, phosphorylated heavy chain, tau, phospho-tau, amyloid beta1-42 from serum/cerebrospinal fluid, and brain atrophy. Neurofilaments related to regional atrophy in bvFTD, whereas progranulin was associated with atrophy in semantic variant PPA. Ubiquitin showed no effects. DISCUSSION: Results specify biomarker and atrophy patterns in FTLD and AD supporting differential diagnosis. They identify neurofilaments and progranulin in interaction with structural imaging as promising candidates for monitoring disease progression and therapy. HIGHLIGHTS: Study cross-validated neuroimaging and fluid biomarkers in dementia. Five kinds of frontotemporal lobar degeneration and two variants of Alzheimer's disease. Study identifies disease-specific fluid biomarker and atrophy profiles. Fluid biomarkers and atrophy interact in a disease-specific way. Neurofilaments and progranulin are proposed as biomarkers for diagnosis and therapy.

Serum Beta-Synuclein Is Higher in Down Syndrome and Precedes Rise of pTau181.

This exploratory case-control study investigates the synaptic marker beta-synuclein in serum and plasma pTau181 in adults with Down syndrome (DS) with (sDS, n = 14) and without (aDS, n = 47) clinical symptoms of Alzheimer disease (AD) as well as euploid controls (n = 23). Beta-synuclein was higher in aDS and more pronounced in sDS (p < 0.0001), whereas pTau181 was only higher in sDS (p < 0.0001). Both markers showed good discriminatory power (area under the curve > 0.90) to distinguish symptomatic from asymptomatic AD. The data indicate that synaptic alterations belong to the earliest AD-associated events in DS and highlight the value of serum beta-synuclein as a potential early marker of AD. ANN NEUROL 2022;92:6-10.

Relationship of serum beta-synuclein with blood biomarkers and brain atrophy.

BACKGROUND: Recent data support beta-synuclein as a blood biomarker to study synaptic degeneration in Alzheimer's disease (AD). METHODS: We provide a detailed comparison of serum beta-synuclein immunoprecipitation - mass spectrometry (IP-MS) with the established blood markers phosphorylated tau 181 (p-tau181) (Simoa) and neurofilament light (NfL) (Ella) in the German FTLD consortium cohort (n = 374) and its relation to brain atrophy (magnetic resonance imaging) and cognitive scores. RESULTS: Serum beta-synuclein was increased in AD but not in frontotemporal lobar degeneration (FTLD) syndromes. Beta-synuclein correlated with atrophy in temporal brain structures and was associated with cognitive impairment. Serum p-tau181 showed the most specific changes in AD but the lowest correlation with structural alterations. NfL was elevated in all diseases and correlated with frontal and temporal brain atrophy. DISCUSSION: Serum beta-synuclein changes differ from those of NfL and p-tau181 and are strongly related to AD, most likely reflecting temporal synaptic degeneration. Beta-synuclein can complement the existing panel of blood markers, thereby providing information on synaptic alterations. HIGHLIGHTS: Blood beta-synuclein is increased in Alzheimer's disease (AD) but not in frontotemporal lobar degeneration (FTLD) syndromes. Blood beta-synuclein correlates with temporal brain atrophy in AD. Blood beta-synuclein correlates with cognitive impairment in AD. The pattern of blood beta-synuclein changes in the investigated diseases is different to phosphorylated tau 181 (p-tau181) and neurofilament light (NfL).

CSF levels of SNAP-25 are increased early in Creutzfeldt-Jakob and Alzheimer's disease.

BACKGROUND: Synaptosomal-associated protein 25 (SNAP-25) in cerebrospinal fluid (CSF) is an emerging synaptic biomarker for the early diagnosis of Alzheimer's disease (AD). However, comprehensive studies investigating the marker in Creutzfeldt-Jakob disease (CJD) and in the differential diagnosis of neurodegenerative diseases are still lacking. METHODS: We developed a novel, sensitive ELISA for the measurement of SNAP-25 in CSF. In total, we analysed 316 patients from 6 diagnostic groups comprising patients with AD (n=96), CJD (n=55), Parkinson's disease spectrum (n=41), frontotemporal lobar degeneration (n=25) and amyotrophic lateral sclerosis (n=24) and non-neurodegenerative control patients (n=75). Using receiver operating characteristic curve analysis, we analysed the differential diagnostic potential and compared the results with core AD biomarkers. RESULTS: SNAP-25 CSF concentrations were elevated in AD and CJD (p<0.0001) but not in the other neurodegenerative diseases. Increased levels were observed already at early AD and CJD stages (p<0.0001). In CJD, SNAP-25 levels correlated negatively with survival time (r=-0.33 (95% CI -0.57 to -0.04, p=0.02). For the discrimination of AD from all other diseases except CJD, we observed a good diagnostic performance for CSF SNAP-25 (area under the curve (AUC) 0.85) which was further improved by applying the ratio with CSF amyloid-ß 1-42 (AUC 0.95). For CJD, we could demonstrate a strong differential diagnostic potential against all other groups including AD (AUC 0.97). CONCLUSION: Using the novel established CSF SNAP-25 ELISA, we here demonstrate the applicability of SNAP-25 as an early synaptic biomarker for both AD and CJD with a possible prognostic value in patients with CJD.

Serum GFAP differentiates Alzheimer's disease from frontotemporal dementia and predicts MCI-to-dementia conversion.

OBJECTIVE: Reactive astrogliosis is a hallmark of Alzheimer's disease (AD) and frontotemporal dementia (FTD) but differences between the diseases and time course are unclear. Here, we used serum levels of the astroglial marker glial fibrillary acidic protein (GFAP) to investigate differences in patients with AD dementia, mild cognitive impairment (MCI)-AD and behavioural variant FTD (bvFTD). METHODS: This multicentre study included serum samples from patients diagnosed with AD dementia (n=230), MCI-AD (n=111), bvFTD (n=140) and controls (n=129). A subgroup of patients with MCI-AD (n=32) was longitudinally followed-up for 3.9±2.6 years after sample collection. Serum levels of GFAP, neurofilament light chain (NfL) and pTau181 were measured by Simoa (Quanterix) and Ella (ProteinSimple). RESULTS: In total, samples from 610 individuals from four clinical centres were investigated in this study. Serum GFAP levels in AD dementia were increased (median 375 pg/mL, IQR 276-505 pg/mL) compared with controls (167 pg/mL, IQR 108-234 pg/mL) and bvFTD (190 pg/mL, IQR 134-298 pg/mL, p<0.001). GFAP was already increased in the early disease phase (MCI-AD, 300 pg/mL, IQR 232-433 pg/mL, p<0.001) and was higher in patients with MCI-AD who developed dementia during follow-up (360 pg/mL, IQR 253-414 pg/mL vs 215 pg/mL, IQR 111-266 pg/mL, p<0.01, area under the curve (AUC)=0.77). Diagnostic performance of serum GFAP for AD (AUC=0.84, sensitivity 98%, specificity 60%, likelihood ratio 2.5) was comparable to serum pTau181 (AUC=0.89, sensitivity 80%, specificity 87%, likelihood ratio 6.0) but superior to serum NfL (AUC=0.71, sensitivity 92%, specificity 49%, likelihood ratio 1.8). CONCLUSIONS: Our data indicate a different type of reactive astrogliosis in AD and bvFTD and support serum GFAP as biomarker for differential diagnosis and prediction of MCI-to-dementia conversion.

Clinico-genetic findings in 509 frontotemporal dementia patients.

Frontotemporal dementia (FTD) is a clinically and genetically heterogeneous disorder. To which extent genetic aberrations dictate clinical presentation remains elusive. We investigated the spectrum of genetic causes and assessed the genotype-driven differences in biomarker profiles, disease severity and clinical manifestation by recruiting 509 FTD patients from different centers of the German FTLD consortium where individuals were clinically assessed including biomarker analysis. Exome sequencing as well as C9orf72 repeat analysis were performed in all patients. These genetic analyses resulted in a diagnostic yield of 18.1%. Pathogenic variants in C9orf72 (n = 47), GRN (n = 26), MAPT (n = 11), TBK1 (n = 5), FUS (n = 1), TARDBP (n = 1), and CTSF (n = 1) were identified across all clinical subtypes of FTD. TBK1-associated FTD was frequent accounting for 5.4% of solved cases. Detection of a homozygous missense variant verified CTSF as an FTD gene. ABCA7 was identified as a candidate gene for monogenic FTD. The distribution of APOE alleles did not differ significantly between FTD patients and the average population. Male sex was weakly associated with clinical manifestation of the behavioral variant of FTD. Age of onset was lowest in MAPT patients. Further, high CSF neurofilament light chain levels were found to be related to GRN-associated FTD. Our study provides large-scale retrospective clinico-genetic data such as on disease manifestation and progression of FTD. These data will be relevant for counseling patients and their families.

Utility of the Repeat and Point Test for Subtyping Patients With Primary Progressive Aphasia.

BACKGROUND: Primary progressive aphasia (PPA) may present with three distinct clinical sybtypes: semantic variant PPA (svPPA), nonfluent/agrammatic variant PPA (nfvPPA), and logopenic variant PPA (lvPPA). OBJECTIVE: The aim was to examine the utility of the German version of the Repeat and Point (R&P) Test for subtyping patients with PPA. METHOD: During the R&P Test, the examiner reads out aloud a noun and the participants are asked to repeat the word and subsequently point to the corresponding picture. Data from 204 patients (68 svPPA, 85 nfvPPA, and 51 lvPPA) and 33 healthy controls were analyzed. RESULTS: Controls completed both tasks with >90% accuracy. Patients with svPPA had high scores in repetition (mean=9.2±1.32) but low scores in pointing (mean=6±2.52). In contrast, patients with nfvPPA and lvPPA performed comparably in both tasks with lower scores in repetition (mean=7.4±2.7 for nfvPPA and 8.2±2.34 for lvPPA) but higher scores in pointing (mean=8.9±1.41 for nfvPPA and 8.6±1.62 for lvPPA). The R&P Test had high accuracy discriminating svPPA from nfvPPA (83% accuracy) and lvPPA (79% accuracy). However, there was low accuracy discriminating nfvPPA from lvPPA (<60%). CONCLUSION: The R&P Test helps to differentiate svPPA from 2 nonsemantic variants (nfvPPA and lvPPA). However, additional tests are required for the differentiation of nfvPPA and lvPPA.

Rational design of antisense oligonucleotides modulating the activity of TLR7/8 agonists.

Oligonucleotide-based therapeutics have become a reality, and are set to transform management of many diseases. Nevertheless, the modulatory activities of these molecules on immune responses remain incompletely defined. Here, we show that gene targeting 2'-O-methyl (2'OMe) gapmer antisense oligonucleotides (ASOs) can have opposing activities on Toll-Like Receptors 7 and 8 (TLR7/8), leading to divergent suppression of TLR7 and activation of TLR8, in a sequence-dependent manner. Surprisingly, TLR8 potentiation by the gapmer ASOs was blunted by locked nucleic acid (LNA) and 2'-methoxyethyl (2'MOE) modifications. Through a screen of 192 2'OMe ASOs and sequence mutants, we characterized the structural and sequence determinants of these activities. Importantly, we identified core motifs preventing the immunosuppressive activities of 2'OMe ASOs on TLR7. Based on these observations, we designed oligonucleotides strongly potentiating TLR8 sensing of Resiquimod, which preserve TLR7 function, and promote strong activation of phagocytes and immune cells. We also provide proof-of-principle data that gene-targeting ASOs can be selected to synergize with TLR8 agonists currently under investigation as immunotherapies, and show that rational ASO selection can be used to prevent unintended immune suppression of TLR7. Taken together, our work characterizes the immumodulatory effects of ASOs to advance their therapeutic development.

Beta-synuclein in cerebrospinal fluid as an early diagnostic marker of Alzheimer's disease.

OBJECTIVE: Synaptic loss plays a major role in Alzheimer's disease (AD). However so far no neurochemical marker for synaptic loss has been introduced into clinical routine. By mass spectrometry beta-synuclein was established as a candidate marker. We now aimed to set up a novel ELISA for beta-synuclein for evaluation of its potential as a diagnostic and predictive marker for AD. METHODS: We analysed in total 393 patients from four specialised centres. The diagnostic groups comprised: AD (n=151), behavioural variant frontotemporal dementia (bvFTD, n=18), Parkinson syndrome (n=46), Creutzfeldt-Jakob disease (CJD, n=23), amyotrophic lateral sclerosis (ALS, n=29), disease control (n=66) and 60 non-neurodegenerative control patients. Results were compared with core AD biomarkers (total tau, phospho-tau and amyloid-ß peptide 1-42). Additionally, coexistence of beta-synuclein with vesicular glutamate transporter 1 (VGLUT1) was determined and beta-synuclein levels were quantified in brain homogenates. RESULTS: Beta-synuclein levels quantified with the newly established ELISA correlated strongly with antibody-free quantitative mass spectrometry data (r=0.92 (95% CI: 0.89 to 0.94), p<0.0001). Cerebrospinal fluid (CSF) beta-synuclein levels were increased in AD-mild cognitive impairment (p<0.0001), AD dementia (p<0.0001) and CJD (p<0.0001), but not in bvFTD, Parkinson syndrome or ALS. Furthermore, beta-synuclein was localised in VGLUT1-positive glutamatergic synapses, and its expression was significantly reduced in brain tissue from patients with AD (p<0.01). CONCLUSION: We successfully established a sensitive and robust ELISA for the measurement of brain-enriched beta-synuclein, which we could show is localised in glutamatergic synapses. We confirmed previous, mass spectrometry-based observations of increased beta-synuclein levels in CSF of patients with AD and CJD supporting its potential use as a marker of synaptic degeneration.

Cerebrospinal Fluid Levels of Prodynorphin-Derived Peptides are Decreased in Huntington's Disease.

RESULTS: Huntington's disease (HD) is a devastating neurodegenerative disorder characterized by a selective loss of striatal medium spiny projection neurons (MSNs). Prodynorphin (PDYN) is enriched in a subpopulation of striatal MSNs. Postmortem brains of HD patients and rodent models have been demonstrated to have reduced levels of PDYN transcripts and the neuropeptide dynorphin. RESULTS: Given the unmet need for novel pharmacodynamic HD biomarkers in the context of experimental huntingtin (htt)-lowering therapies, we investigated the levels of PDYN-derived peptides and neurofilament light (NfL) chain in the cerebrospinal fluid (CSF) from HD patients (n = 16), matched controls (n = 55), and patients with other neurodegenerative disorders (n = 70). RESULTS: PDYN-derived peptide levels were found to be substantially decreased in HD patients (P < 0.0001 in comparison to controls), whereas the NfL levels were elevated in all neurodegenerative disorders. CONCLUSIONS: Our study suggests decreased PDYN-derived peptide levels in the CSF as a more specific biomarker for HD in comparison to NfL. © 2020 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Quantifying progression in primary progressive aphasia with structural neuroimaging.

INTRODUCTION: The term primary progressive aphasia (PPA) sums up the non-fluent (nfv), the semantic (sv), and the logopenic (lv) variant. Up to now, there is only limited data available concerning magnetic resonance imaging volumetry to monitor disease progression. METHODS: Structural brain imaging and an extensive assessment were applied at baseline and up to 4-year(s) follow-up in 269 participants. With automated atlas-based volumetry 56 brain regions were assessed. Atrophy progression served to calculate sample sizes for therapeutic trials. RESULTS: At baseline highest atrophy appeared in parts of the left frontal lobe for nfvPPA (-17%) and of the left temporal lobe for svPPA (-34%) and lvPPA (-24%). Severest progression within 1-year follow-up occurred in the basal ganglia in nfvPPA (-7%), in the hippocampus/amygdala in svPPA (-9%), and in (medial) temporal regions in lvPPA (-6%). CONCLUSION: PPA presents as a left-dominant, mostly gray matter sensitive disease with considerable atrophy at baseline that proceeds variant-specific.

[Amyotrophic lateral sclerosis and frontotemporal dementia-On the way to common gene-specific treatment approaches]. / Amyotrophe Lateralsklerose und frontotemporale Demenz ­ auf dem Weg zu gemeinsamen genspezifischen Therapieansätzen.

BACKGROUND: Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) share common neuropathological features and in the case of a gene mutation, also a genetic cause. To date five ALS-FTD genes are described in the literature in addition to other rare variants. OBJECTIVE: The current state of research on treatment options for ALS and FTD is presented and an outlook on possible gene-specific approaches for ALS-FTD is provided. MATERIAL AND METHODS: Analysis of the progression of ALS and FTD research by considering the increasing state of knowledge on the underlying pathomechanisms of the diseases. RESULTS: In addition to anti-inflammatory approaches and stabilization of protein folding, promising gene-specific treatment approaches are currently being developed, which target common causes of ALS and FTD and therefore have an effect on both diseases. CONCLUSION: So far there are no causal treatment options for ALS and FTD. The increasing importance of genetic causes directs the focus to the development of gene-specific treatment.

Targeted Mass Spectrometry Suggests Beta-Synuclein as Synaptic Blood Marker in Alzheimer's Disease.

Synaptic degeneration is a major hallmark of Alzheimer's disease (AD) and the best pathological correlate of cognitive dysfunction. Synaptic markers are therefore a highly desired read-out for patient diagnosis and possible follow-up in clinical trials. Several synaptic markers for AD are described in cerebrospinal fluid (CSF), but studies in blood have failed so far. Using quantitative mass spectrometry (IP-MS, MRM) we observed increased concentrations of the presynaptic protein beta-synuclein (ßSyn) in CSF and blood of AD patients (n = 64, p < 0.01) and confirmed this finding in two validation cohorts (AD: n = 40 and n = 49, controls: n = 44 and n = 25). ßSyn was already increased in patients with mild cognitive impairment (p < 0.01) and was also markedly increased in Creutzfeldt-Jakob disease (CJD; n = 25, p < 0.001) but not behavioral variant frontotemporal dementia (n = 16), dementia with Lewy bodies/Parkinson's disease dementia (n = 13), Parkinson's disease (n = 25), or amyotrophic lateral sclerosis (n = 30). The diagnostic sensitivity and specificity for CJD versus other neurodegenerative diseases was ≥96%. These findings suggest ßSyn as a candidate blood marker for synaptic degeneration that might be used in clinical AD trials and patient follow-up as part of the recently suggested ATN biomarker panel. It can also serve in the differential diagnosis of CJD.

Different CSF protein profiles in amyotrophic lateral sclerosis and frontotemporal dementia with C9orf72 hexanucleotide repeat expansion.

OBJECTIVES: The hexanucleotide repeat expansion in the C9orf72 gene is the most common mutation associated with amyotrophic lateral sclerosis (C9-ALS) and frontotemporal dementia (C9-FTD). Until now, it is unknown which factors define whether C9orf72 mutation carriers develop ALS or FTD. Our aim was to identify protein biomarker candidates in the cerebrospinal fluid (CSF) which differentiate between C9-ALS and C9-FTD and might be indicative for the outcome of the mutation. METHODS: We compared the CSF proteome of 16 C9-ALS and 8 C9-FTD patients and 11 asymptomatic C9orf72 mutation carriers (CAR) by isobaric tags for relative and absolute quantitation. Eleven biomarker candidates were selected from the pool of differentially regulated proteins for further validation by multiple reaction monitoring and single-molecule array in a larger cohort (n=156). RESULTS: In total, 2095 CSF proteins were identified and 236 proteins were significantly different in C9-ALS versus C9-FTD including neurofilament medium polypeptide (NEFM) and chitotriosidase-1 (CHIT1). Eight candidates were successfully validated including significantly increased ubiquitin carboxyl-terminal hydrolase isozyme L1 (UCHL1) levels in C9-ALS compared with C9-FTD and controls and decreased neuronal pentraxin receptor (NPTXR) levels in C9-FTD versus CAR. CONCLUSIONS: This study presents a deep proteomic CSF analysis of C9-ALS versus C9-FTD patients. As a proof of concept, we observed higher NEFM and CHIT1 CSF levels in C9-ALS. In addition, we also show clear upregulation of UCHL1 in C9-ALS and downregulation of NPTXR in C9-FTD. Significant differences in UCHL1 CSF levels may explain diverging ubiquitination and autophagy processes and NPTXR levels might reflect different synapses organisation processes.

Story of the ALS-FTD continuum retold: rather two distinct entities.

OBJECTIVE: To determine the evolution and profile of cognitive and behavioural deficits in amyotrophic lateral sclerosis (ALS) and behavioural variant frontotemporal dementia (bvFTD) to disentangle the development of FTD in ALS and vice versa. METHODS: In a prospective design, cognitive and behavioural profiles of 762 patients with motor predominant ALS (flail arm/leg syndrome, primary lateral sclerosis, pseudobulbar palsy, ALS) and behavioural predominant FTD (bvFTD, ALS-FTD) were determined and caregivers of patients with ALS were asked on the evolution of behavioural symptoms. Data were compared with 49 healthy controls. Cognition was measured with the Edinburgh Cognitive and Behavioral ALS Screen. RESULTS: Evolution and features of cognitive profile of patients with motor predominant ALS were distinctly different from patients with behavioural FTD with regard to number and degree of affected cognitive domains. Also, in ALS mostly minus symptoms evolved after physical symptom onset whereas in ALS-FTD plus and minus symptoms were reported with an onset before physical degradation. CONCLUSION: Evolution of cognitive and behavioural profile in patients with motor predominant ALS is distinctly different from those psychocognitive findings in patients with behavioural variant dementia. This may support the hypothesis that (possibly genetic) triggers decide in the preclinical phase on either motor or psychocognitive phenotypes.

Different neuroinflammatory profile in amyotrophic lateral sclerosis and frontotemporal dementia is linked to the clinical phase.

OBJECTIVE: To investigate the role of neuroinflammation in asymptomatic and symptomatic amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) mutation carriers. METHODS: The neuroinflammatory markers chitotriosidase 1 (CHIT1), YKL-40 and glial fibrillary acidic protein (GFAP) were measured in cerebrospinal fluid (CSF) and blood samples from asymptomatic and symptomatic ALS/FTD mutation carriers, sporadic cases and controls by ELISA. RESULTS: CSF levels of CHIT1, YKL-40 and GFAP were unaffected in asymptomatic mutation carriers (n=16). CHIT1 and YKL-40 were increased in gALS (p<0.001, n=65) whereas GFAP was not affected. Patients with ALS carrying a CHIT1 polymorphism had lower CHIT1 concentrations in CSF (-80%) whereas this polymorphism had no influence on disease severity. In gFTD (n=23), increased YKL-40 and GFAP were observed (p<0.05), whereas CHIT1 was nearly not affected. The same profile as in gALS and gFTD was observed in sALS (n=64/70) and sFTD (n=20/26). CSF and blood concentrations correlated moderately (CHIT1, r=0.51) to weak (YKL-40, r=0.30, GFAP, r=0.39). Blood concentrations of these three markers were not significantly altered in any of the groups except CHIT1 in gALS of the Ulm cohort (p<0.05). CONCLUSION: Our data indicate that neuroinflammation is linked to the symptomatic phase of ALS/FTD and shows a similar pattern in sporadic and genetic cases. ALS and FTD are characterised by a different neuroinflammatory profile, which might be one driver of the diverse presentations of the ALS/FTD syndrome.

Chitotriosidase (CHIT1) is increased in microglia and macrophages in spinal cord of amyotrophic lateral sclerosis and cerebrospinal fluid levels correlate with disease severity and progression.

OBJECTIVES: Neurochemical markers of amyotrophic lateral sclerosis (ALS) that reflect underlying disease mechanisms might help in diagnosis, staging and prediction of outcome. We aimed at determining the origin and differential diagnostic and prognostic potential of the putative marker of microglial activation chitotriosidase (CHIT1). METHODS: Altogether 316 patients were included, comprising patients with sporadic ALS, ALS mimics (disease controls (DCo)), frontotemporal lobar degeneration (FTLD), Creutzfeldt-Jakob disease (CJD), Alzheimer's disease (AD), Parkinson's disease (PD) and healthy controls (Con). CHIT1 and neurofilament levels were determined in cerebrospinal fluid (CSF) and blood and analysed with regard to diagnostic sensitivity and specificity and prognostic performance. Additionally, postmortem tissue was analysed for CHIT1 expression. RESULTS: In ALS, CHIT1 CSF levels were higher compared with Con (p<0.0001), DCo (p<0.05) and neurodegenerative diseases (AD p<0.05, PD p<0.01, FTLD p<0.0001) except CJD. CHIT1 concentrations were correlated with ALS disease progression and severity but not with the survival time, as did neurofilaments. Serum CHIT1 levels were not different in ALS compared with any other study group. In the spinal cord of patients with ALS, but not Con, AD or CJD cases, CHIT1 was expressed in the corticospinal tract and CHIT1 staining colocalised with markers of microglia (IBA1) and macrophages (CD68). CONCLUSIONS: CHIT1 concentrations in the CSF of patients with ALS may reflect the extent of microglia/macrophage activation in the white matter of the spinal cord. CHIT1 could be a potentially useful marker for differential diagnosis and prediction of disease progression in ALS and, therefore, seems suitable as a supplemental marker for patient stratification in therapeutic trials.

Pittsburgh compound B imaging and cerebrospinal fluid amyloid-ß in a multicentre European memory clinic study.

The aim of this study was to assess the agreement between data on cerebral amyloidosis, derived using Pittsburgh compound B positron emission tomography and (i) multi-laboratory INNOTEST enzyme linked immunosorbent assay derived cerebrospinal fluid concentrations of amyloid-ß42; (ii) centrally measured cerebrospinal fluid amyloid-ß42 using a Meso Scale Discovery enzyme linked immunosorbent assay; and (iii) cerebrospinal fluid amyloid-ß42 centrally measured using an antibody-independent mass spectrometry-based reference method. Moreover, we examined the hypothesis that discordance between amyloid biomarker measurements may be due to interindividual differences in total amyloid-ß production, by using the ratio of amyloid-ß42 to amyloid-ß40 Our study population consisted of 243 subjects from seven centres belonging to the Biomarkers for Alzheimer's and Parkinson's Disease Initiative, and included subjects with normal cognition and patients with mild cognitive impairment, Alzheimer's disease dementia, frontotemporal dementia, and vascular dementia. All had Pittsburgh compound B positron emission tomography data, cerebrospinal fluid INNOTEST amyloid-ß42 values, and cerebrospinal fluid samples available for reanalysis. Cerebrospinal fluid samples were reanalysed (amyloid-ß42 and amyloid-ß40) using Meso Scale Discovery electrochemiluminescence enzyme linked immunosorbent assay technology, and a novel, antibody-independent, mass spectrometry reference method. Pittsburgh compound B standardized uptake value ratio results were scaled using the Centiloid method. Concordance between Meso Scale Discovery/mass spectrometry reference measurement procedure findings and Pittsburgh compound B was high in subjects with mild cognitive impairment and Alzheimer's disease, while more variable results were observed for cognitively normal and non-Alzheimer's disease groups. Agreement between Pittsburgh compound B classification and Meso Scale Discovery/mass spectrometry reference measurement procedure findings was further improved when using amyloid-ß42/40 Agreement between Pittsburgh compound B visual ratings and Centiloids was near complete. Despite improved agreement between Pittsburgh compound B and centrally analysed cerebrospinal fluid, a minority of subjects showed discordant findings. While future studies are needed, our results suggest that amyloid biomarker results may not be interchangeable in some individuals.

Neurofilaments in the diagnosis of motoneuron diseases: a prospective study on 455 patients.

OBJECTIVES: Biomarkers for the diagnosis of motoneuron diseases (MND) are urgently needed to improve the diagnostic pathway, patient stratification and monitoring. The aim of this study was to validate candidate markers for MND in cerebrospinal fluid (CSF) and specify cut-offs based on large patient cohorts by especially considering patients who were seen under the initial differential diagnosis (MND mimics). METHODS: In a prospective study, we investigated CSF of 455 patients for neurofilament light chain (NfL), phosphorylated heavy chain (pNfH), tau protein (Tau) and phospho-tau protein (pTau). Analysed cohorts included patients with apparently sporadic and familial amyotrophic lateral sclerosis (ALS) and primary lateral sclerosis (PLS) (MND, n=253), MND mimics (n=85) and neurological control groups. Cut-off values were specified, and diagnostic performance and correlation with progression were analysed. RESULTS: Nfs were significantly higher in the MND group compared to the control groups, whereas Tau and pTau did not differ. At a cut-off level of 2200 pg/mL for NfL, a 77% diagnostic sensitivity (CI 71% to 82%), 85% specificity (CI 79% to 90%) and 87% positive predictive value (PPV) (CI 81% to 91%) were achieved. For pNfH, we calculated 83% sensitivity (CI 78% to 88%), 77% specificity (CI 71% to 83%) and 82% PPV (CI 77% to 86%) at 560 pg/mL. There were no significant differences between sporadic and genetic ALS or PLS. Nf levels were elevated at early disease stage, and correlated moderately with MND progression and duration. CONCLUSIONS: Neurofilaments in CSF have a high relevance for the differential diagnosis of MNDs and should be included in the diagnostic work-up of patients. Their value as prognostic markers should be investigated further.

Intact protein analysis of ubiquitin in cerebrospinal fluid by multiple reaction monitoring reveals differences in Alzheimer's disease and frontotemporal lobar degeneration.

The impairment of the ubiquitin-proteasome system (UPS) is thought to be an early event in neurodegeneration, and monitoring UPS alterations might serve as a disease biomarker. Our aim was to establish an alternate method to antibody-based assays for the selective measurement of free monoubiquitin in cerebrospinal fluid (CSF). Free monoubiquitin was measured with liquid chromatography-multiple reaction monitoring mass spectrometry (LC-MS/MS) in CSF of patients with Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), behavioral variant of frontotemporal dementia (bvFTD), Creutzfeldt-Jakob disease (CJD), Parkinson's disease (PD), primary progressive aphasia (PPA), and progressive supranuclear palsy (PSP). The LC-MS/MS method showed excellent intra- and interassay precision (4.4-7.4% and 4.9-10.3%) and accuracy (100-107% and 100-106%). CSF ubiquitin concentration was increased compared with that of controls (33.0 ± 9.7 ng/mL) in AD (47.5 ± 13.1 ng/mL, p < 0.05) and CJD patients (171.5 ± 103.5 ng/mL, p < 0.001) but not in other neurodegenerative diseases. Receiver operating characteristic curve (ROC) analysis of AD vs control patients revealed an area under the curve (AUC) of 0.832, and the specificity and sensitivity were 75 and 75%, respectively. ROC analysis of AD and FTLD patients yielded an AUC of 0.776, and the specificity and sensitivity were 53 and 100%, respectively. In conclusion, our LC-MS/MS method may facilitate ubiquitin determination to a broader community and might help to discriminate AD, CJD, and FTLD patients.