Detection of TDP-43 seeding activity in the olfactory mucosa from patients with frontotemporal dementia.

INTRODUCTION: We assessed TAR DNA-binding protein 43 (TDP-43) seeding activity and aggregates detection in olfactory mucosa of patients with frontotemporal lobar degeneration with TDP-43-immunoreactive pathology (FTLD-TDP) by TDP-43 seeding amplification assay (TDP43-SAA) and immunocytochemical analysis. METHODS: The TDP43-SAA was optimized using frontal cortex samples from 16 post mortem cases with FTLD-TDP, FTLD with tau inclusions, and controls. Subsequently, olfactory mucosa samples were collected from 17 patients with FTLD-TDP, 15 healthy controls, and three patients carrying MAPT variants. RESULTS: TDP43-SAA discriminated with 100% accuracy post mortem cases presenting or lacking TDP-43 neuropathology. TDP-43 seeding activity was detectable in the olfactory mucosa, and 82.4% of patients with FTLD-TDP tested positive, whereas 86.7% of controls tested negative (P < 0.001). Two out of three patients with MAPT mutations tested negative. In TDP43-SAA positive samples, cytoplasmatic deposits of phosphorylated TDP-43 in the olfactory neural cells were detected. DISCUSSION: TDP-43 aggregates can be detectable in olfactory mucosa, suggesting that TDP43-SAA might be useful for identifying and monitoring FTLD-TDP in living patients.

Enhanced expression of the autophagosomal marker LC3-II in detergent-resistant protein lysates from a CLN3 patient's post-mortem brain.

• Neuronal Ceroido Lipofuscinoses (NCL) are inherited, neurodegenerative disorders associated with lysosomal storage. • Impaired autophagy plays a pathogenetic role in several NCL forms, including CLN3 disease, but study on human brains are lacking. • In post-mortem brain samples of a CLN3 patient the LC3-I to LC3-II shift was consistent with activated autophagy. However, the autophagic process seemed to be ineffective due to the presence of lysosomal storage markers. • After fractionation with buffers of increasing detergent-denaturing strength, a peculiar solubility pattern of LC3-II was observed in CLN3 patient's samples, suggesting a different lipid composition of the membranes where LC3-II is stacked.

Corrigendum: PMCA-based detection of prions in the olfactory mucosa of patients with sporadic Creutzfeldt-Jakob disease.

[This corrects the article DOI: 10.3389/fnagi.2022.848991.].

Sporadic Creutzfeldt-Jakob disease is associated with reorganization of metabolic connectivity in a pathological brain network.

BACKGROUND AND PURPOSE: Although sporadic Creutzfeldt-Jakob disease (sCJD) is a rare cause of dementia, it is critical to understand its functional networks as the prion protein spread throughout the brain may share similar mechanisms with other more common neurodegenerative disorders. In this study, the metabolic brain network associated with sCJD was investigated and its internal network organization was explored. METHODS: We explored 2-[18 F]fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET) brain scans of 29 sCJD patients, 56 normal controls (NCs) and 46 other dementia patients from two independent centers. sCJD-related pattern (CJDRP) was identified in a cohort of 16 pathologically proven sCJD patients and 16 age-matched NCs using scaled subprofile modeling/principal component analysis and was prospectively validated in an independent cohort of 13 sCJD patients and 20 NCs. The pattern's specificity was tested on other dementia patients and its clinical relevance by clinical correlations. The pattern's internal organization was further studied using graph theory methods. RESULTS: The CJDRP was characterized by relative hypometabolism in the bilateral caudate, thalami, middle and superior frontal gyri, parietal lobe and posterior cingulum in association with relative hypermetabolism in the hippocampi, parahippocampal gyri and cerebellum. The pattern's expression significantly discriminated sCJD from NCs and other dementia patients (p < 0.005; receiver operating characteristic analysis CJD vs. NCs area under the curve [AUC] 0.90-0.96, sCJD vs. Alzheimer's disease AUC 0.78, sCJD vs. behavioral variant of frontotemporal dementia AUC 0.84). The pattern's expression significantly correlated with cognitive, functional decline and disease duration. The metabolic connectivity analysis revealed inefficient information transfer with specific network reorganization. CONCLUSIONS: The CJDRP is a robust metabolic biomarker of sCJD. Due to its excellent clinical correlations it has the potential to monitor disease in emerging disease-modifying trials.

Biochemical and Neuropathological Findings in a Creutzfeldt-Jakob Disease Patient with the Rare Val180Ile-129Val Haplotype in the Prion Protein Gene.

Genetic Creutzfeldt-Jakob disease (gCJD) associated with the V180I mutation in the prion protein (PrP) gene (PRNP) in phase with residue 129M is the most frequent cause of gCJD in East Asia, whereas it is quite uncommon in Caucasians. We report on a gCJD patient with the rare V180I-129V haplotype, showing an unusually long duration of the disease and a characteristic pathological PrP (PrPSc) glycotype. Family members carrying the mutation were fully asymptomatic, as commonly observed with this mutation. Neuropathological examination showed a lesion pattern corresponding to that commonly reported in Japanese V180I cases with vacuolization and gliosis of the cerebral cortexes, olfactory areas, hippocampus and amygdala. PrP was deposited with a punctate, synaptic-like pattern in the cerebral cortex, amygdala and olfactory tract. Western blot analyses of proteinase-K-resistant PrP showed the characteristic two-banding pattern of V180I gCJD, composed of mono- and un-glycosylated isoforms. In line with reports on other V180I cases in the literature, Real-Time Quaking Induced Conversion (RT-QuIC) analyses did not demonstrate the presence of seeding activity in the cerebrospinal fluid and olfactory mucosa, suggesting that this haplotype also may result in a reduced seeding efficiency of the pathological PrP. Further studies are required to understand the origin, penetrance, disease phenotype and transmissibility of 180I-129V haplotype in Caucasians.

Olfactory swab sampling optimization for α-synuclein aggregate detection in patients with Parkinson's disease.

BACKGROUND: In patients with Parkinson's disease (PD), real-time quaking-induced conversion (RT-QuIC) detection of pathological α-synuclein (α-syn) in olfactory mucosa (OM) is not as accurate as in other α-synucleinopathies. It is unknown whether these variable results might be related to a different distribution of pathological α-syn in OM. Thus, we investigated whether nasal swab (NS) performed in areas with a different coverage by olfactory neuroepithelium, such as agger nasi (AN) and middle turbinate (MT), might affect the detection of pathological α-syn. METHODS: NS was performed in 66 patients with PD and 29 non-PD between September 2018 and April 2021. In 43 patients, cerebrospinal fluid (CSF) was also obtained and all samples were analyzed by RT-QuIC for α-syn. RESULTS: In the first round, 72 OM samples were collected by NS, from AN (NSAN) or from MT (NSMT), and 35 resulted positive for α-syn RT-QuIC, including 27/32 (84%) from AN, 5/11 (45%) from MT, and 3/29 (10%) belonging to the non-PD patients. Furthermore, 23 additional PD patients underwent NS at both AN and MT, and RT-QuIC revealed α-syn positive in 18/23 (78%) NSAN samples and in 10/23 (44%) NSMT samples. Immunocytochemistry of NS preparations showed a higher representation of olfactory neural cells in NSAN compared to NSMT. We also observed α-syn and phospho-α-syn deposits in NS from PD patients but not in controls. Finally, RT-QuIC was positive in 22/24 CSF samples from PD patients (92%) and in 1/19 non-PD. CONCLUSION: In PD patients, RT-QuIC sensitivity is significantly increased (from 45% to 84%) when NS is performed at AN, indicating that α-syn aggregates are preferentially detected in olfactory areas with higher concentration of olfactory neurons. Although RT-QuIC analysis of CSF showed a higher diagnostic accuracy compared to NS, due to the non-invasiveness, NS might be considered as an ancillary procedure for PD diagnosis.

PMCA-Based Detection of Prions in the Olfactory Mucosa of Patients With Sporadic Creutzfeldt-Jakob Disease.

Sporadic Creutzfeldt-Jakob disease (sCJD) is a rare neurodegenerative disorder caused by the conformational conversion of the prion protein (PrPC) into an abnormally folded form, named prion (or PrPSc). The combination of the polymorphism at codon 129 of the PrP gene (coding either methionine or valine) with the biochemical feature of the proteinase-K resistant PrP (generating either PrPSc type 1 or 2) gives rise to different PrPSc strains, which cause variable phenotypes of sCJD. The definitive diagnosis of sCJD and its classification can be achieved only post-mortem after PrPSc identification and characterization in the brain. By exploiting the Real-Time Quaking-Induced Conversion (RT-QuIC) assay, traces of PrPSc were found in the olfactory mucosa (OM) of sCJD patients, thus demonstrating that PrPSc is not confined to the brain. Here, we have optimized another technique, named protein misfolding cyclic amplification (PMCA) for detecting PrPSc in OM samples of sCJD patients. OM samples were collected from 27 sCJD and 2 genetic CJD patients (E200K). Samples from 34 patients with other neurodegenerative disorders were included as controls. Brains were collected from 26 sCJD patients and 16 of them underwent OM collection. Brain and OM samples were subjected to PMCA using the brains of transgenic mice expressing human PrPC with methionine at codon 129 as reaction substrates. The amplified products were analyzed by Western blot after proteinase K digestion. Quantitative PMCA was performed to estimate PrPSc concentration in OM. PMCA enabled the detection of prions in OM samples with 79.3% sensitivity and 100% specificity. Except for a few cases, a predominant type 1 PrPSc was generated, regardless of the tissues analyzed. Notably, all amplified PrPSc were less resistant to PK compared to the original strain. In conclusion, although the optimized PMCA did not consent to recognize sCJD subtypes from the analysis of OM collected from living patients, it enabled us to estimate for the first time the amount of prions accumulating in this biological tissue. Further assay optimizations are needed to faithfully amplify peripheral prions whose recognition could lead to a better diagnosis and selection of patients for future clinical trials.

Alpha-synuclein seeds in olfactory mucosa and cerebrospinal fluid of patients with dementia with Lewy bodies.

In patients with suspected dementia with Lewy bodies, the detection of the disease-associated α-synuclein in easily accessible tissues amenable to be collected using minimally invasive procedures remains a major diagnostic challenge. This approach has the potential to take advantage of modern molecular assays for the diagnosis of α-synucleinopathy and, in turn, to optimize the recruitment and selection of patients in clinical trials, using drugs directed at counteracting α-synuclein aggregation. In this study, we explored the diagnostic accuracy of α-synuclein real-time quaking-induced conversion assay by testing olfactory mucosa and CSF in patients with a clinical diagnosis of probable (n = 32) or prodromal (n = 5) dementia with Lewy bodies or mixed degenerative dementia (dementia with Lewy bodies/Alzheimer's disease) (n = 6). Thirty-eight patients with non-α-synuclein-related neurodegenerative and non-neurodegenerative disorders, including Alzheimer's disease (n = 10), sporadic Creutzfeldt-Jakob disease (n = 10), progressive supranuclear palsy (n = 8), corticobasal syndrome (n = 1), fronto-temporal dementia (n = 3) and other neurological conditions (n = 6) were also included, as controls. All 81 patients underwent olfactory swabbing while CSF was obtained in 48 participants. At the initial blinded screening of olfactory mucosa samples, 38 out of 81 resulted positive while CSF was positive in 19 samples out of 48 analysed. After unblinding of the results, 27 positive olfactory mucosa were assigned to patients with probable dementia with Lewy bodies, five with prodromal dementia with Lewy bodies and three to patients with mixed dementia, as opposed to three out 38 controls. Corresponding results of CSF testing disclosed 10 out 10 positive samples in patients with probable dementia with Lewy bodies and six out of six with mixed dementia, in addition to three out of 32 for controls. The accuracy among results of real-time quaking-induced conversion assays and clinical diagnoses was 86.4% in the case of olfactory mucosa and 93.8% for CSF. For the first time, we showed that α-synuclein real-time quaking-induced conversion assay detects α-synuclein aggregates in olfactory mucosa of patients with dementia with Lewy bodies and with mixed dementia. Additionally, we provided preliminary evidence that the combined testing of olfactory mucosa and CSF raised the concordance with clinical diagnosis potentially to 100%. Our results suggest that nasal swabbing might be considered as a first-line screening procedure in patients with a diagnosis of suspected dementia with Lewy bodies followed by CSF analysis, as a confirmatory test, when the result in the olfactory mucosa is incongruent with the initial clinical diagnosis.

Alpha-synuclein seeds in olfactory mucosa of patients with isolated REM sleep behaviour disorder.

Isolated REM sleep behaviour disorder (RBD) is an early-stage α-synucleinopathy in most, if not all, affected subjects. Detection of pathological α-synuclein in peripheral tissues of patients with isolated RBD may identify those progressing to Parkinson's disease, dementia with Lewy bodies or multiple system atrophy, with the ultimate goal of testing preventive therapies. Real-time quaking-induced conversion (RT-QuIC) provided evidence of α-synuclein seeding activity in CSF and olfactory mucosa of patients with α-synucleinopathies. The aim of this study was to explore RT-QuIC detection of α-synuclein aggregates in olfactory mucosa of a large cohort of subjects with isolated RBD compared to patients with Parkinson's disease and control subjects. This cross-sectional case-control study was performed at the Medical University of Innsbruck, Austria, the Hospital Clinic de Barcelona, Spain, and the University of Verona, Italy. Olfactory mucosa samples obtained by nasal swab in 63 patients with isolated RBD, 41 matched Parkinson's disease patients and 59 matched control subjects were analysed by α-synuclein RT-QuIC in a blinded fashion at the University of Verona, Italy. Median age of patients with isolated RBD was 70 years, 85.7% were male. All participants were tested for smell, autonomic, cognitive and motor functions. Olfactory mucosa was α-synuclein RT-QuIC positive in 44.4% isolated RBD patients, 46.3% Parkinson's disease patients and 10.2% control subjects. While the sensitivity for isolated RBD plus Parkinson's disease versus controls was 45.2%, specificity was high (89.8%). Among isolated RBD patients with positive α-synuclein RT-QuIC, 78.6% had olfactory dysfunction compared to 21.4% with negative α-synuclein RT-QuIC (P < 0.001). The extent of olfactory dysfunction was more severe in isolated RBD patients positive than negative for olfactory mucosa a-synuclein RT-QuIC (P < 0.001). We provide evidence that the α-synuclein RT-QuIC assay enables the molecular detection of neuronal α-synuclein aggregates in olfactory mucosa of patients with isolated RBD and Parkinson's disease. Although the overall sensitivity was moderate in this study, nasal swabbing is attractive as a simple, non-invasive test and might be useful as part of a screening battery to identify subjects in the prodromal stages of α-synucleinopathies. Further studies are needed to enhance sensitivity, and better understand the temporal dynamics of α-synuclein seeding in the olfactory mucosa and spreading to other brain areas during the progression from isolated RBD to overt α-synucleinopathy, as well the impact of timing, disease subgroups and sampling technique on the overall sensitivity.

Ring trial of 2nd generation RT-QuIC diagnostic tests for sporadic CJD.

OBJECTIVE: Real-time quaking-induced conversion (RT-QuIC) assays detect prion-seeding activity in a variety of human biospecimens, including cerebrospinal fluid and olfactory mucosa swabs. The assay has shown high diagnostic accuracy in patients with prion disorders. Recently, advances in these tests have led to markedly improved diagnostic sensitivity and reduced assay times. Accordingly, an algorithm has been proposed that entails the use of RT-QuIC analysis of both sample types to diagnose sporadic Creutzfeldt-Jakob disease with nearly 100% accuracy. Here we present a multi-center evaluation (ring trial) of the reproducibility of these improved "second generation" RT-QuIC assays as applied to these diagnostic specimens. METHODS: Cerebrospinal fluid samples were analyzed from subjects with sporadic Creutzfeldt-Jakob (n = 55) or other neurological diseases (n = 45) at multiple clinical centers. Olfactory mucosa brushings collected by multiple otolaryngologists were obtained from nine sporadic Creutzfeldt-Jakob disease cases and 19 controls. These sample sets were initially tested blindly by RT-QuIC by a coordinating laboratory, recoded, and then sent to five additional testing laboratories for blinded ring trial testing. RESULTS: Unblinding of the results by a third party indicated 98-100% concordance between the results obtained by the testing of these cerebrospinal fluid and nasal brushings at the six laboratories. INTERPRETATION: This second-generation RT-QuIC assay is highly transferrable, reproducible, and therefore robust for the diagnosis of sporadic Creutzfeldt-Jakob disease in clinical practice.

Genetic variants of TAS2R38 bitter taste receptor associate with distinct gut microbiota traits in Parkinson's disease: A pilot study.

The non-tasting form of the bitter taste receptor, TAS2R38, has been shown as a genetic risk factor associated with the development of Parkinson's disease (PD). Specific taste receptors that are expressed in the lower gastrointestinal tract may respond to alteration in gut microbiota composition, detecting bacterial molecules, and regulate immune responses. Given the importance of brain-gut-microbiota axis and gene-environment interactions in PD, we investigate the associations between the genetic variants of TAS2R38 and gut microbiota composition in 39 PD patients. The results confirm that the majority of PD patients have reduced sensitivity to 6-n-propylthiouracil (PROP) and are carriers of at least one non-functional TAS2R38 AVI haplotype. Moreover, we found this correlation to be associated with a reduction in bacteria alpha-diversity with a predominant reduction of Clostridium genus. We hypothesised that the high frequency of the non-taster form of TAS2R38 associated with a diminuition of Clostridium bacteria in PD might determine a reduction in the activation of protective signalling-molecules useful in preserving gut homeostasis. This pilot study, by identifying a decrease in specific bacteria associated with a reduced sensitivity to PROP, adds essential information that opens new avenues of research into the association of PD microbiota composition and sensory modification.

Transmission of CJD from nasal brushings but not spinal fluid or RT-QuIC product.

OBJECTIVE: The detection of prion seeding activity in CSF and olfactory mucosal brushings using real-time quaking-induced conversion assays allows highly accurate clinical diagnosis of sporadic Creutzfeldt-Jakob disease. To gauge transmission risks associated with these biospecimens and their testing, we have bioassayed prion infectivity levels in patients' brain tissue, nasal brushings, and CSF, and assessed the pathogenicity of amplified products of real-time quaking-induced conversion assays seeded with Creutzfeldt-Jakob disease prions. METHODS: We obtained olfactory mucosal brushings and CSF from patients with a final diagnosis of sporadic Creutzfeldt-Jakob disease subtype MM1 (n = 3). Samples were inoculated intracerebrally into Tg66 transgenic mice that overexpress the homologous human 129M prion protein. The mice were evaluated for clinical, neuropathological, and biochemical evidence of prion infection. RESULTS: Patients' brain tissue at 102 to 105 fold dilutions affected 47/48 Tg66 mice. In contrast, maximum acutely tolerable doses of insoluble pellets from their olfactory mucosa brushings caused evidence of prion disease in only 4/28 inoculated mice, and no effects were seen with 10-fold dilutions. No clinical prion disease was observed in mice inoculated with antemortem CSF samples or prion-seeded real-time quaking-induced conversion assay products. INTERPRETATION: Pellets from patients' olfactory mucosa brushings had ≥10,000-fold lower infectivity per unit volume than brain tissue, while CSF lacked detectable infectivity. Nonetheless, the results suggest that appropriate precautions may be warranted in surgical interventions involving the olfactory areas. The lack of pathogenic infectivity in the real-time quaking-induced conversion assay products provides evidence that the assay does not replicate biohazardous prions in vitro.

A case of MV2K subtype of sporadic Creutzfeldt-Jakob disease with florid-like plaques: Similarities and differences to variant Creutzfeldt-Jakob disease.

Variant Creutzfeldt-Jakob disease (vCJD) is traditionally regarded as having a distinct clinical course, imaging study findings and neuropathological features, which in combination should allow a clear distinction from the six currently well-defined subtypes of sporadic Creutzfeldt-Jakob disease (sCJD). This is of major importance, especially from the standpoint of epidemiology. As we would like to demonstrate through this case report, the MV2K subtype of sCJD, being rare and heterogeneous in both clinical and neuropathological presentations, might challenge this concept by virtue of partial overlapping, both clinically and neuropathologically, with the characteristic phenotype of vCJD. Chiefly, we observed prolonged isolated psychiatric prodrome, new onset limb pain and late cognitive decline clinically, while florid-like plaques were present on routine histology, albeit in scarce and regionally restricted distribution when compared to vCJD. However, the issue is further complicated by the fact that a case of vCJD in a heterozygous (i.e. methionine - M and valine - V) allelic state with regard to the polymorphic codon 129 of the prion protein gene (PRNP) has recently been described in the UK, which deviated from the otherwise well-defined and constant clinicopathological phenotype that vCJD had thus far demonstrated. Taking both the facts into account, we would like to emphasize the use of complementary diagnostic methods to the established and otherwise reliable histological type-based model, particularly when confronted with a rare or atypical phenotype such as ours.

Anti-Cholinergic Derangement of Cortical Metabolism on 18F-FDG PET in a Patient with Frontotemporal Lobar Degeneration Dementia: A Case of the TREDEM Registry.

We present the case of a patient with an atypical course of frontotemporal lobar degeneration (FTLD) complicated by the use of an anticholinergic drug. A 70-year-old patient, followed by psychiatrists for depression and behavioral disorders, received a diagnosis of dementia with Lewy bodies (DLB) at another Center due to auditory hallucinations, gait impairment, and tendency to fall. He was then admitted to our Memory Clinic Unit for behavioral disturbances, such as delusional thinking, auditory hallucinations, and memory complaints. At that time, the patient's therapy included Lorazepam, Quetiapine, Promazine, and Biperiden. The latter was immediately suspended for the absence of extrapyramidal signs and to avoid the anticholinergic cognitive side effects. A 18F-FDG PET showed a derangement of cortical metabolism with diffusely reduced activity, and limited areas of hyperactivity involving lateral frontal and lateral temporal inferior regions bilaterally. The patient underwent a series of exams, including neuropsychological tests, 123I-MIBG scintigraphy, cerebrospinal fluid examination, and genetic analysis. A second 18F-FDG PET showed an extensive remodulation of metabolic activity: relative higher concentration of the tracer in the prefrontal and inferior temporal cortex was no more detectable. Similarly, the diffuse reduced metabolic activity could not be traced anymore. Nonetheless, the metabolic activity still appeared reduced in the frontal lobe, in the anterior cingulate bilaterally, and in the anterior part of the hemispheric fissure. Taken together, clinical and neuroimaging features would point to a FTLD-like form. Furthermore, the diagnostic work-up was likely confounded by the anticholinergic drug on 18F-FDG PET, highlighting the importance of carefully checking the patient's pharmacology during the diagnostic process.

High Diagnostic Accuracy of RT-QuIC Assay in a Prospective Study of Patients with Suspected sCJD.

The early and accurate in vivo diagnosis of sporadic Creutzfeldt-Jakob disease (sCJD) is essential in order to differentiate CJD from treatable rapidly progressive dementias. Diagnostic investigations supportive of clinical CJD diagnosis include magnetic resonance imaging (MRI), electroencephalogram (EEG), 14-3-3 protein detection, and/or real-time quaking-induced conversion (RT-QuIC) assay positivity in the cerebrospinal fluid (CSF) or in other tissues. The total CSF tau protein concentration has also been used in a clinical setting for improving the CJD diagnostic sensitivity and specificity. We analyzed 182 CSF samples and 42 olfactory mucosa (OM) brushings from patients suspected of having sCJD with rapidly progressive dementia (RPD), in order to determine the diagnostic accuracy of 14-3-3, the total tau protein, and the RT-QuIC assay. A probable and definite sCJD diagnosis was assessed in 102 patients. The RT-QuIC assay on the CSF samples showed a 100% specificity and a 96% sensitivity, significantly higher compared with 14-3-3 (84% sensitivity and 46% specificity) and tau (85% sensitivity and 70% specificity); however, the combination of RT-QuIC testing of the CSF and OM samples resulted in 100% sensitivity and specificity, proving a significantly higher accuracy of RT-QuIC compared with the surrogate biomarkers in the diagnostic setting of patients with RPD. Moreover, we showed that CSF blood contamination or high protein levels might interfere with RT-QuIC seeding. In conclusion, we provided further evidence that the inclusion of an RT-QuIC assay of the CSF and OM in the diagnostic criteria for sCJD has radically changed the clinical approach towards the diagnosis.

α-Synuclein RT-QuIC assay in cerebrospinal fluid of patients with dementia with Lewy bodies.

We applied RT-QuIC assay to detect α-synuclein aggregates in cerebrospinal fluid (CSF) of patients with suspected Creutzfeldt-Jakob disease who had a neuropathological diagnosis of dementia with Lewy bodies (DLB) (n = 7), other neurodegenerative diseases with α-synuclein mixed pathology (n = 20), or without Lewy-related pathology (n = 49). The test had a sensitivity of 92.9% and specificity of 95.9% in distinguishing α-synucleinopathies from non-α-synucleinopathies. When performed in the CSF of patients with DLB (n = 36), RT-QuIC was positive in 17/20 with probable DLB, 0/6 with possible DLB, and 0/10 with Alzheimer disease. These results indicate that RT-QuIC for α-synuclein is an accurate test for DLB diagnosis.

Reappraisal of Aß40 and Aß42 Peptides Measurements in Cerebrospinal Fluid of Patients with Alzheimer's Disease.

Cerebrospinal fluid (CSF) biomarkers are currently included in the diagnostic criteria for Alzheimer's disease (AD), in particular, decreased concentrations of amyloid-ß peptide 1-42 (Aß42) in the CSF, coupled with increased levels of tau and phosphorylated tau proteins, are supportive of AD diagnosis. To date, the quantification of Aß42 levels with antibody-dependent immunoassay shows a marked variability among different laboratories and is also affected by different pre-analytical factors, suggesting that part of Aß42 peptides might be aggregated and thus undetected by antibodies. To bypass an antibody-dependent measurement, we determined the Aß40 and Aß42 levels by immunoblot. We analyzed CSF samples from 35 patients with clinical diagnosis of probable AD and from 15 age-matched normal controls; CSF Aß levels were determined by two different ELISA kits and by immunoblot analysis. Aß40 levels measured by ELISA were comparable to those obtained by immunoblot, whereas CSF concentrations of Aß42 measured by ELISA were significantly lower compared to values obtained by immunoblot quantification. Biochemical analysis, following 1D- and 2D-PAGE analysis, showed that the qualitative composition of Aß peptides in the CSF is similar in AD and controls but different from that of AD brain tissues. Moreover, sedimentation velocity in sucrose gradient of CSF and brain homogenate from AD demonstrated that Aß42 in CSF is different from Aß42 in brain in terms of solubility and aggregation state.

Biochemical Characterization of Prions.

Prion disease or transmissible spongiform encephalopathies are characterized by the presence of the abnormal form of the prion protein (PrPSc). The pathological and transmissible properties of PrPSc are enciphered in its secondary and tertiary structures. Since it's well established that different strains of prions are linked to different conformations of PrPSc, biochemical characterization of prions seems a preliminary but reliable approach to detect, analyze, and compare prion strains. Experimental biochemical procedures might be helpful in distinguishing PrPSc physicochemical properties and include resistance to proteinase K (PK) digestion, insolubility in nonionic detergents, PK-resistance under denaturing conditions and sedimentation properties in sucrose gradients. This biochemical approach has been extensively applied in human prion disorders and subsequently expanded for PrPSc characterization in animals. In particular, in sporadic Creutzfedlt-Jakob disease (sCJD) PrPSc is characterized by two main glycotypes conventionally named Type 1 and Type 2, based on the apparent gel migration at 21 and 19kDa of the PrPSc PK-resistant fragment. An additional PrPSc type was identified in sCJD characterized by an unglycosylated dominant glycoform pattern and in 2010 a variably protease-sensitive prionopathy (VPSPr) was reported showing a PrPSc with an electrophoretic ladder like pattern. Additionally, the presence of PrPSc truncated fragments completes the electrophoretic characterization of different prion strains. By two-dimensional (2D) electrophoretic analysis additional PrPSc pattern was identified, since this procedure provides information about the isoelectric point and the different peptides length related to PK cleavage, as well as to glycosylation extent or GPI anchor presence. We here provide and extensive review on PrPSc biochemical analysis in human and animal prion disorders. Further, we show that PrPSc glycotypes observed in CJD share similarities with PrPSc in bovine spongiform encephalopathy forms (BSE).

Microglial and Neuronal TDP-43 Pathology in Anti-IgLON5-Related Tauopathy.

A novel neuronal tauopathy, mainly confined to hypothalamus and brainstem tegmentum, has recently been reported in patients with autoantibodies to the neuronal cell-adhesion molecule IgLON5. We describe a patient with anti-IgLON5 syndrome, who presented with dysautonomia and sleep disorder, followed by subacute dementia. Postmortem brain examination disclosed neuronal tau pathology prevailing in the hippocampus, amygdala, and locus coeruleus, in addition to microglial/neuronal TDP-43 pathology, with overexpression of aberrantly phosphorylated forms and neurotoxic truncated fragments, in basal ganglia, nucleus basalis, thalamus, and midbrain. These findings suggest that neurodegeneration in anti-IgLON5 syndrome might also occur via a microglia-triggered non-cell autonomous pathway.