Sporadic and familial CJD: classification and characterisation

Sleep disturbance in clinical and preclinical scrapie-infected sheep measured by polysomnography

Neurodegenerative diseases are characterised by neuronal loss and abnormal deposition of pathological proteins in the nervous system. Among the most common neurodegenerative diseases are Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease and transmissible spongiform encephalopathies (TSEs). Sleep and circadian rhythm disturbances are one of the most common symptoms in patients with neurodegenerative diseases. Currently, one of the main objectives in the study of TSEs is to try to establish an early diagnosis, as clinical signs do not appear until the damage to the central nervous system is very advanced, which prevents any therapeutic approach. In this paper, we provide the first description of sleep disturbance caused by classical scrapie in clinical and preclinical sheep using polysomnography compared to healthy controls. Fifteen sheep classified into three groups, clinical, preclinical and negative control, were analysed. The results show a decrease in total sleep time as the disease progresses, with significant changes between control, clinical and pre-clinical animals. The results also show an increase in sleep fragmentation in clinical animals compared to preclinical and control animals. In addition, sheep with clinical scrapie show a total loss of Rapid Eye Movement sleep (REM) and alterations in Non Rapid Eyes Movement sleep (NREM) compared to control sheep, demonstrating more shallow sleep. Although further research is needed, these results suggest that prion diseases also produce sleep disturbances in animals and that polysomnography could be a diagnostic tool of interest in clinical and preclinical cases of prion diseases.

A systemic analysis of Creutzfeldt Jakob disease cases in Asia

Creutzfeldt Jakob Disease (CJD) is a rapidly progressive, fatal neurodegenerative disorder, also known as a subacute spongiform encephalopathy. There are three major subtypes of CJD i.e. Sporadic CJD, which occurs for reasons unbeknown to science (85% of known cases), Genetic or Familial CJD which is characterized by the presence of mutations in the human prion protein (PRNP) gene (10-15% cases) and Iatrogenic CJD that occurs via accidental transmission through medical and surgical procedures (1-2% cases). CJD cases occur globally with 1 case per one million population/year. Considerable data is available related to the incidence and prevalence of CJD in Europe and America. However, the global surveillance database is yet to include Asia even though several Asian countries have their own CJD monitoring units. sCJD is the highest among all CJD cases in Asia. China (1957) and Japan (1705) have reported more cases of sCJD than any Asian country and Hong Kong (1) has reported the least. On the other hand, gCJD is highest in Japan (370) and least in India (2). Our analysis establishes the presence of all variants of CJD across Asia. However, in most Asian countries in general and Southeast Asian countries in particular, CJD cases are misdiagnosed and often underreported. Since Asia is the most populated continent in the world, the actual global prevalence of CJD cannot be estimated until and unless these countries are accounted for. Concrete and reliable surveillance networks are needed across Asia to evaluate the prevalence and incidence of CJD in the region. [Figure: see text]The graphical abstract demonstrates the prevalence of CJD cases in the world and systematically analyses the incidence of CJD in Asian countries between the year 1986-2022. Highest number of cases were reported in Japan followed by China. The study emphasizes the need for assimilation of Asian data in global prevalence.

Sporadic Creutzfeldt-Jakob disease in adults over 80 years: a 10-year review of United Kingdom surveillance

INTRODUCTION

Sporadic Creutzfeldt-Jakob disease (sCJD) is a rapidly progressive neurodegenerative disease with public health implications. Mean age of onset is 68 years. Age-specific incidence declines after 80 years. This may arise from under-ascertainment or other biological features of the disease. Accurate characterisation of late-onset sCJD is important for early diagnosis, avoiding unnecessary investigations and improving ascertainment for public health purposes.

OBJECTIVE

To phenotype the clinical features and investigation profile of sCJD in adults >80 years.

METHODS

We analysed all probable and definite sCJD cases identified by the UK National CJD Research & Surveillance Unit over a 10-year period (2011-2021). Individuals were grouped by age of onset. Clinical features and investigation profiles were compared.

RESULTS

10.3% (123/1196) had an age of onset over 80. Median survival was shorter (3.2 vs 4.3 months; P < 0.001). Pyramidal signs (48.3% vs 34.2%; P = 0.008) and akinetic mutism (55.1% vs 33.2%; P < 0.001) were more frequent. Psychiatric symptoms (26.3% vs 39.6%; P = 0.01) and cerebellar signs (65.4% vs 78.6%, P = 0.007) were less frequent. Cognitive impairment and myoclonus were highly prevalent regardless of age. Between age groups, the diagnostic sensitivity of cerebrospinal fluid real-time quaking-induced conversion (CSF RT-QuIC) (92.9% vs 91.9%, P = 0.74) was comparable, electroencephalography was superior (41.5% vs 25.4%; P = 0.006) and MRI was inferior (67.8% vs 91.4%; P < 0.001).

CONCLUSIONS

Late-onset sCJD has distinct clinical features, shorter survival and a different profile of investigation sensitivity. CSF RT-QuIC, MRI brain and specialist CJD review is recommended in older adults with a rapidly progressive neurological disorder. Autopsy is valuable when the cause remains elusive.

Efficient transmission of human prion diseases to a glycan-free prion protein-expressing host

It is increasingly evident that the association of glycans with the prion protein (PrP), a major post-translational modification, significantly impacts the pathogenesis of prion diseases. A recent bioassay study has provided evidence that the presence of PrP glycans decreases spongiform degeneration and disease-related PrP (PrPD) deposition in a murine model. We challenged (PRNPN181Q/197Q) transgenic (Tg) mice expressing glycan-free human PrP (TgGlyc-), with isolates from sporadic Creutzfeldt-Jakob disease subtype MM2 (sCJDMM2), sporadic fatal insomnia and familial fatal insomnia, three human prion diseases that are distinct but share histotypic and PrPD features. TgGlyc- mice accurately replicated the basic histotypic features associated with the three diseases but the transmission was characterized by high attack rates, shortened incubation periods and a greatly increased severity of the histopathology, including the presence of up to 40 times higher quantities of PrPD that formed prominent deposits. Although the engineered protease-resistant PrPD shared at least some features of the secondary structure and the presence of the anchorless PrPD variant with the wild-type PrPD, it exhibited different density gradient profiles of the PrPD aggregates and a higher stability index. The severity of the histopathological features including PrP deposition appeared to be related to the incubation period duration. These findings are clearly consistent with the protective role of the PrP glycans but also emphasize the complexity of the conformational changes that impact PrPD following glycan knockout. Future studies will determine whether these features apply broadly to other human prion diseases or are PrPD-type dependent.

Progressive supranuclear palsy phenotype as an atypical clinical presentation of Creutzfeldt-Jakob disease: A case report and review of the literature

Creutzfeldt-Jakob disease (CJD) is a rare, rapidly progressive neurodegenerative disorder, characterized by the accumulation of abnormal prion proteins in the brain. While CJD has some typical clinical features, its presentation can be quite heterogeneous, particularly in the early stages of the disease, posing challenges in diagnosis. Atypical manifestations of CJD can mimic various neurodegenerative disorders, including atypical parkinsonisms. In this case report, we present an 81-year-old man who exhibited an atypical clinical presentation of sporadic CJD, initially resembling progressive supranuclear palsy (PSP). The patient presented with symmetric parkinsonism, postural instability, and ocular motor dysfunction, accompanied by rapid clinical deterioration. Alongside the case report, we also provide a review of the literature on atypical presentations of CJD as PSP, highlighting the importance of recognizing these manifestations in clinical practice.

Large-scale validation of skin prion seeding activity as a biomarker for diagnosis of prion diseases

Definitive diagnosis of sporadic Creutzfeldt-Jakob disease (sCJD) relies on the examination of brain tissues for the pathological prion protein (PrPSc). Our previous study revealed that PrPSc-seeding activity (PrPSc-SA) is detectable in skin of sCJD patients by an ultrasensitive PrPSc seed amplification assay (PrPSc-SAA) known as real-time quaking-induced conversion (RT-QuIC). A total of 875 skin samples were collected from 2 cohorts (1 and 2) at autopsy from 2-3 body areas of 339 cases with neuropathologically confirmed prion diseases and non-sCJD controls. The skin samples were analyzed for PrPSc-SA by RT-QuIC assay. The results were compared with demographic information, clinical manifestations, cerebrospinal fluid (CSF) PrPSc-SA, other laboratory tests, subtypes of prion diseases defined by the methionine (M) or valine (V) polymorphism at residue 129 of PrP, PrPSc types (#1 or #2), and gene mutations in deceased patients. RT-QuIC assays of the cohort #1 by two independent laboratories gave 87.3% or 91.3% sensitivity and 94.7% or 100% specificity, respectively. The cohort #2 showed sensitivity of 89.4% and specificity of 95.5%. RT-QuIC of CSF available from 212 cases gave 89.7% sensitivity and 94.1% specificity. The sensitivity of skin RT-QuIC was subtype dependent, being highest in sCJDVV1-2 subtype, followed by VV2, MV1-2, MV1, MV2, MM1, MM1-2, MM2, and VV1. The skin area next to the ear gave highest sensitivity, followed by lower back and apex of the head. Although no difference in brain PrPSc-SA was detected between the cases with false negative and true positive skin RT-QuIC results, the disease duration was significantly longer with the false negatives [12.0 ± 13.3 (months, SD) vs. 6.5 ± 6.4, p < 0.001]. Our study validates skin PrPSc-SA as a biomarker for the detection of prion diseases, which is influenced by the PrPSc types, PRNP 129 polymorphisms, dermatome sampled, and disease duration.

Detection of prions in the urine of patients affected by sporadic Creutzfeldt-Jakob disease

OBJECTIVE

Currently, it is unknown whether infectious prions are present in peripheral tissues and biological fluids of patients affected by sporadic Creutzfeldt-Jakob disease (sCJD), the most common prion disorder in humans. This represents a potential risk for inter-individual prion infection. The main goal of this study was to evaluate the presence of prions in urine of patients suffering from the major subtypes of sCJD.

METHODS

Urine samples from sCJD patients spanning the six major subtypes were tested. As controls, we used urine samples from people affected by other neurological or neurodegenerative diseases as well as healthy controls. These samples were analyzed blinded. The presence of prions was detected by a modified version of the PMCA technology, specifically optimized for high sensitive detection of sCJD prions.

RESULTS

The PMCA assay was first optimized to detect low quantities of prions in diluted brain homogenates from patients affected by all subtypes of sCJD spiked into healthy urine. Twenty-nine of the 81 patients affected by sCJD analyzed in this study were positive by PMCA testing, whereas none of the 160 controls showed any signal. These results indicate a 36% sensitivity and 100% specificity. The subtypes with the highest positivity rate were VV1 and VV2, which combined account for about 15-20% of all sCJD cases, and no detection was observed in MV1 and MM2.

INTERPRETATION

Our findings indicate that potentially infectious prions are secreted in urine of some sCJD patients, suggesting a possible risk for inter-individual transmission. Prion detection in urine might be used as a noninvasive preliminary screening test to detect sCJD.

Elevated E200K Somatic Mutation of the Prion Protein Gene (PRNP) in the Brain Tissues of Patients with Sporadic Creutzfeldt-Jakob Disease (CJD)

Sporadic Creutzfeldt-Jakob disease (CJD) is a major human prion disease worldwide. CJD is a fatal neurodegenerative disease caused by an abnormal prion protein (PrPSc). To date, the exact etiology of sporadic CJD has not been fully elucidated. We investigated the E200K and V203I somatic mutations of the prion protein gene (PRNP) in sporadic CJD patients and matched healthy controls using pyrosequencing. In addition, we estimated the impact of somatic mutations on the human prion protein (PrP) using PolyPhen-2, PANTHER and PROVEAN. Furthermore, we evaluated the 3D structure and electrostatic potential of the human PrP according to somatic mutations using DeepView. The rates of PRNP K200 somatic mutation were significantly increased in the frontal cortex and hippocampus of sporadic CJD patients compared to the matched controls. In addition, the electrostatic potential of the human PrP was significantly changed by the K200 somatic mutation of the PRNP gene. To the best of our knowledge, this is the first report on an association of the PRNP K200 somatic mutation with sporadic CJD.

Neuronal Ndst1 depletion accelerates prion protein clearance and slows neurodegeneration in prion infection

Select prion diseases are characterized by widespread cerebral plaque-like deposits of amyloid fibrils enriched in heparan sulfate (HS), a abundant extracellular matrix component. HS facilitates fibril formation in vitro, yet how HS impacts fibrillar plaque growth within the brain is unclear. Here we found that prion-bound HS chains are highly sulfated, and that the sulfation is essential for accelerating prion conversion in vitro. Using conditional knockout mice to deplete the HS sulfation enzyme, Ndst1 (N-deacetylase / N-sulfotransferase) from neurons or astrocytes, we investigated how reducing HS sulfation impacts survival and prion aggregate distribution during a prion infection. Neuronal Ndst1-depleted mice survived longer and showed fewer and smaller parenchymal plaques, shorter fibrils, and increased vascular amyloid, consistent with enhanced aggregate transit toward perivascular drainage channels. The prolonged survival was strain-dependent, affecting mice infected with extracellular, plaque-forming, but not membrane bound, prions. Live PET imaging revealed rapid clearance of recombinant prion protein monomers into the CSF of neuronal Ndst1- deficient mice, neuronal, further suggesting that HS sulfate groups hinder transit of extracellular prion protein monomers. Our results directly show how a host cofactor slows the spread of prion protein through the extracellular space and identify an enzyme to target to facilitate aggregate clearance.

Novel histotypes of sporadic Creutzfeldt-Jakob disease linked to 129MV genotype

The MV1 and MV2 subtypes of sporadic Creutzfeldt-Jakob disease (sCJD) are linked to the heterozygous methionine (M)/valine (V) polymorphism at codon 129 of the prion protein (PrP) gene. MV2 is phenotypically heterogeneous, whereas MV1, due to its low prevalence, is one of the least well characterized subtypes. In this study, we investigated the biochemical properties of PrPSc and phenotypic expression of cases diagnosed as sCJD MV1 and MV2. We describe four MV2 histotypes: 2C, with cortical (C) coarse pathology; 2K, with kuru (K) plaque deposits; 2C-K, with co-existing C and K histotypic features; and the novel histotype 2C-PL that mimics 2C in the cerebral cortex and cerebellum, but exhibits plaque-like (PL) PrP deposits in subcortical regions (e.g., basal nuclei, thalamus and midbrain). Histotype prevalence is highest for 2C-K (55%), intermediate for 2C (31%), and lowest for 2C-PL and 2K (7%). Nearly every MV2 case expressed both PrPSc types, with T2 being the predominant type ("MV2-1"). MV1 cases typically show a rapid disease course (≤ 4 months), and feature the 1C histotype, phenotypically identical to sCJDMM1. Co-existing PrPSc types, with T1 significantly exceeding T2 ("MV1-2"), are detected in patients diagnosed as MV1 with longer disease courses. We observed four histotypes among MV1-2 cases, including two novel histotypes: 1V, reminiscent of sCJDVV1; 1C-2C, resembling sCJDMM1-2 with predominant MM1 histotypic component; and novel histotypes 1C-2PL and 1C-2K, overall mimicking 1C in the cerebral cortex, but harboring T2 and plaque-like PrP deposits in subcortical regions (1C-2PL), and T2 and kuru plaques in the cerebellum (1C-2K). Lesion profiles of 1C, 1V, and 1C-2C are similar, but differ from 1C-2PL and 1C-2K, as the latter two groups show prominent hippocampal and nigral degeneration. We believe that the novel "C-PL" histotypes are distinct entities rather than intermediate forms between "C" and "C-K" groups, and that 1C-2PL and 1C-2K histotypes may be characterized by different T1 variants of the same size.

A discriminative event-based model for subtype diagnosis of sporadic Creutzfeldt-Jakob disease using brain MRI

INTRODUCTION

Sporadic Creutzfeldt-Jakob disease (sCJD) comprises multiple subtypes (MM1, MM2, MV1, MV2C, MV2K, VV1, and VV2) with distinct disease durations and spatiotemporal cascades of brain lesions. Our goal was to establish the ante mortem diagnosis of sCJD subtype, based on patient-specific estimates of the spatiotemporal cascade of lesions detected by diffusion-weighted magnetic resonance imaging (DWI).

METHODS

We included 488 patients with autopsy-confirmed diagnosis of sCJD subtype and 50 patients with exclusion of prion disease. We applied a discriminative event-based model (DEBM) to infer the spatiotemporal cascades of lesions, derived from the DWI scores of 12 brain regions assigned by three neuroradiologists. Based on the DEBM cascades and the prion protein genotype at codon 129, we developed and validated a novel algorithm for the diagnosis of the sCJD subtype.

RESULTS

Cascades of MM1, MM2, MV1, MV2C, and VV1 originated in the parietal cortex and, following subtype-specific orderings of propagation, went toward the striatum, thalamus, and cerebellum; conversely, VV2 and MV2K cascades showed a striatum-to-cortex propagation. The proposed algorithm achieved 76.5% balanced accuracy for the sCJD subtype diagnosis, with low rater dependency (differences in accuracy of ± 1% among neuroradiologists).

DISCUSSION

Ante mortem diagnosis of sCJD subtype is feasible with this novel data-driven approach, and it may be valuable for patient prognostication, stratification in targeted clinical trials, and future therapeutics.

HIGHLIGHTS

Subtype diagnosis of sporadic Creutzfeldt-Jakob disease (sCJD) is achievable with diffusion MRI. Cascades of diffusion MRI abnormalities in the brain are subtype-specific in sCJD. We proposed a diagnostic algorithm based on cascades of diffusion MRI abnormalities and demonstrated that it is accurate. Our method may aid early diagnosis, prognosis, stratification in clinical trials, and future therapeutics. The present approach is applicable to other neurodegenerative diseases, enhancing the differential diagnoses.

A novel subtype of sporadic Creutzfeldt-Jakob disease with PRNP codon 129MM genotype and PrP plaques

The presence of amyloid kuru plaques is a pathological hallmark of sporadic Creutzfeldt-Jakob disease (sCJD) of the MV2K subtype. Recently, PrP plaques (p) have been described in the white matter of a small group of CJD (p-CJD) cases with the 129MM genotype and carrying resPrPD type 1 (T1). Despite the different histopathological phenotype, the gel mobility and molecular features of p-CJD resPrPD T1 mimic those of sCJDMM1, the most common human prion disease. Here, we describe the clinical features, histopathology, and molecular properties of two distinct PrP plaque phenotypes affecting the gray matter (pGM) or the white matter (pWM) of sCJD cases with the PrP 129MM genotype (sCJDMM). Prevalence of pGM- and pWM-CJD proved comparable and was estimated to be ~ 0.6% among sporadic prion diseases and ~ 1.1% among the sCJDMM group. Mean age at onset (61 and 68 years) and disease duration (~ 7 months) of pWM- and pGM-CJD did not differ significantly. PrP plaques were mostly confined to the cerebellar cortex in pGM-CJD, but were ubiquitous in pWM-CJD. Typing of resPrPD T1 showed an unglycosylated fragment of ~ 20 kDa (T120) in pGM-CJD and sCJDMM1 patients, while a doublet of ~ 21-20 kDa (T121-20) was a molecular signature of pWM-CJD in subcortical regions. In addition, conformational characteristics of pWM-CJD resPrPD T1 differed from those of pGM-CJD and sCJDMM1. Inoculation of pWM-CJD and sCJDMM1 brain extracts to transgenic mice expressing human PrP reproduced the histotype with PrP plaques only in mice challenged with pWM-CJD. Furthermore, T120 of pWM-CJD, but not T121, was propagated in mice. These data suggest that T121 and T120 of pWM-CJD, and T120 of sCJDMM1 are distinct prion strains. Further studies are required to shed light on the etiology of p-CJD cases, particularly those of T120 of the novel pGM-CJD subtype.

The advances in the early and accurate diagnosis of Creutzfeldt-Jakob disease and other prion diseases: where are we today?

INTRODUCTION

Before the introduction of MRI diffusion-weighted images (DWI), the diagnosis of Creutzfeldt-Jakob disease (CJD) relied upon nonspecific findings including clinical symptoms, EEG abnormalities, and elevated levels of cerebrospinal fluid 14-3-3 protein. Subsequently, the use of DWI has improved diagnostic accuracy, but it sometimes remains difficult to differentiate CJD from encephalitis, epilepsy, and other dementing disorders. The revised diagnostic criteria include real-time quaking-induced conversion (RT-QuIC), detecting small amounts of CJD-specific prion protein, and clinically sensitive DWI. Combining these techniques has further improved diagnostic accuracy, enabling earlier diagnosis.

AREAS COVERED

Herein, the authors review the recent advances in diagnostic methods and revised diagnostic criteria for sporadic CJD. They also discuss other prion diseases, such as variant CJD and chronic wasting disease, where the emergence of new types is a concern.

EXPERT OPINION

Despite improvements in diagnostic methods and criteria, some subtypes of prion disease are still difficult to diagnose, and even the diagnosis using the most innovative RT-QuIC test remains a challenge in terms of accuracy and standardization. However, these revised criteria can be adapted to the emergence of new types of prion diseases. It is essential to continue careful surveillance and update information on the latest prion disease phenotypes.

Diminished Neuronal ESCRT-0 Function Exacerbates AMPA Receptor Derangement and Accelerates Prion-Induced Neurodegeneration

Endolysosomal defects in neurons are central to the pathogenesis of prion and other neurodegenerative disorders. In prion disease, prion oligomers traffic through the multivesicular body (MVB) and are routed for degradation in lysosomes or for release in exosomes, yet how prions impact proteostatic pathways is unclear. We found that prion-affected human and mouse brain showed a marked reduction in Hrs and STAM1 (ESCRT-0), which route ubiquitinated membrane proteins from early endosomes into MVBs. To determine how the reduction in ESCRT-0 impacts prion conversion and cellular toxicity in vivo, we prion-challenged conditional knockout mice (male and female) having Hrs deleted from neurons, astrocytes, or microglia. The neuronal, but not astrocytic or microglial, Hrs-depleted mice showed a shortened survival and an acceleration in synaptic derangements, including an accumulation of ubiquitinated proteins, deregulation of phosphorylated AMPA and metabotropic glutamate receptors, and profoundly altered synaptic structure, all of which occurred later in the prion-infected control mice. Finally, we found that neuronal Hrs (nHrs) depletion increased surface levels of the cellular prion protein, PrPC, which may contribute to the rapidly advancing disease through neurotoxic signaling. Taken together, the reduced Hrs in the prion-affected brain hampers ubiquitinated protein clearance at the synapse, exacerbates postsynaptic glutamate receptor deregulation, and accelerates neurodegeneration.SIGNIFICANCE STATEMENT Prion diseases are rapidly progressive neurodegenerative disorders characterized by prion aggregate spread through the central nervous system. Early disease features include ubiquitinated protein accumulation and synapse loss. Here, we investigate how prion aggregates alter ubiquitinated protein clearance pathways (ESCRT) in mouse and human prion-infected brain, discovering a marked reduction in Hrs. Using a prion-infection mouse model with neuronal Hrs (nHrs) depleted, we show that low neuronal Hrs is detrimental and markedly shortens survival time while accelerating synaptic derangements, including ubiquitinated protein accumulation, indicating that Hrs loss exacerbates prion disease progression. Additionally, Hrs depletion increases the surface distribution of prion protein (PrPC), linked to aggregate-induced neurotoxic signaling, suggesting that Hrs loss in prion disease accelerates disease through enhancing PrPC-mediated neurotoxic signaling.

Hypothesis: functional age and onset of autosomal dominant genetic prion disease

Autosomal dominant diseases typically have an age-related onset. Here, I focus on genetic prion disease (gPrD), caused by various mutations in the PRNP gene. While gPrD typically occurs at or after middle age, there can be considerable variability in the specific age of onset. This variability can occur among patients with the same PRNP mutation; in some cases, these differences occur not only between families but even within the same family. It is not known why gPrD onset is typically delayed for decades when the causative mutation is present from birth. Mouse models of gPrD manifest disease; however, unlike human gPrD, which typically takes decades to manifest, mouse models exhibit disease within months. Therefore, the time to onset of prion disease is proportional to species lifespan; however, it is not known why this is the case. I hypothesize that the initiation of gPrD is strongly influenced by the process of aging; therefore, disease onset is related to proportional functional age (e.g., mice vs. humans). I propose approaches to test this hypothesis and discuss its significance with respect to delaying prion disease through suppression of aging.

Clinical profiles and ethnic heterogeneity of sporadic fatal insomnia

BACKGROUND AND PURPOSE

This study was undertaken to elucidate the clinical profile of sporadic fatal insomnia (sFI), assess the similarities and differences between sFI and fatal familial insomnia (FFI), and evaluate the influence of ethnicity on the phenotype of sFI patients.

METHODS

The data of sFI and FFI patients were retrieved from our case series and through literature review. The clinical and diagnostic features of sFI and FFI were compared, as were the phenotypes of Asian and Caucasian sFI patients.

RESULTS

We identified 44 sFI and 157 FFI cases. The prevalence of sleep-related, neuropsychiatric, and autonomic symptoms among the sFI patients were 65.9%, 100.0%, and 43.2%, respectively. Compared to FFI, sFI exhibited longer disease duration and a higher proportion of neuropsychiatric symptoms, whereas FFI was characterized by a higher incidence of sleep-related and autonomic symptoms in the early stages of the disease or throughout its course. In addition, a higher proportion of the sFI patients showed hyperintensity on magnetic resonance imaging (MRI) and periodic sharp wave complexes on electroencephalography compared to the FFI patients, especially those presenting with pathological changes associated with MM2-cortical type sporadic Creutzfeldt-Jakob disease. The Asian sFI patients had a higher proportion of males and positivity for cerebrospinal fluid 14-3-3 protein, and fewer sleep-related symptoms compared to Caucasian sFI patients. The age at onset and duration of sFI differed between ethnic groups, but the difference failed to reach statistical significance.

CONCLUSIONS

Despite its similarities to FFI, sFI is characterized by longer disease duration, higher proportion of neuropsychiatric symptoms, and hyperintensity on MRI, along with differences in the clinical characteristics based on ethnicity.

Development of an Automated Capillary Immunoassay to Detect Prion Glycotypes in Creutzfeldt-Jakob Disease

Creutzfeldt-Jakob disease (CJD) comprises a group of transmissible neurodegenerative diseases with vast phenotypic diversity. Sporadic CJD heterogeneity is predominantly influenced by the genotype at codon 129 of the prion-encoding gene and the molecular weight of PrP^Sc fragments after protease digestion, resulting in a classification of 6 subtypes of CJD (MM1, MM2, MV1, MV2, VV1, and VV2). The majority of cases with CJD can be distinguished using this classification system. However, a number of reported CJD cases are phenotypically unique from others within their same subtype, such as variably protease-sensitive prionopathies, or exist as a mixture of subtypes within the same patient. Western blotting of brain tissue, along with the genotyping of codon 129 of the prion-encoding gene, is considered the "gold standard" for the biochemical characterization of CJD. Western blotting requires a significant amount of prion protein for detection, is labor-intensive, and is also associated with high interassay variability. In addition to these limitations, a growing body of research suggests that unique subtypes of CJD are often undetected or misdiagnosed using standard diagnostic western blotting protocols. Consequently, we successfully optimized and developed a capillary-based western assay using the JESS Simple Western (ProteinSimple) to detect and characterize prion proteins from patients with CJD. We found that this novel assay consistently differentiated CJD type 1 and type 2 cases with a limit of detection 10 to 100× higher than traditional western blotting. Cases with CJD in which type 1 and type 2 coexist within the same brain region can be detected using type 1-specific and type 2-specific antibodies, and we found that there was remarkable specificity for the detection of cases with variably protease-sensitive prionopathy. The assay presented displays outstanding sensitivity, allowing for the preservation of valuable samples and enhancing current detection methods.

Sporadic Creutzfeldt-Jakob disease infected human cerebral organoids retain the original human brain subtype features following transmission to humanized transgenic mice

Human cerebral organoids (COs) are three-dimensional self-organizing cultures of cerebral brain tissue differentiated from induced pluripotent stem cells. We have recently shown that COs are susceptible to infection with different subtypes of Creutzfeldt-Jakob disease (CJD) prions, which in humans cause different manifestations of the disease. The ability to study live human brain tissue infected with different CJD subtypes opens a wide array of possibilities from differentiating mechanisms of cell death and identifying neuronal selective vulnerabilities to testing therapeutics. However, the question remained as to whether the prions generated in the CO model truly represent those in the infecting inoculum. Mouse models expressing human prion protein are commonly used to characterize human prion disease as they reproduce many of the molecular and clinical phenotypes associated with CJD subtypes. We therefore inoculated these mice with COs that had been infected with two CJD subtypes (MV1 and MV2) to see if the original subtype characteristics (referred to as strains once transmitted into a model organism) of the infecting prions were maintained in the COs when compared with the original human brain inocula. We found that disease characteristics caused by the molecular subtype of the disease associated prion protein were similar in mice inoculated with either CO derived material or human brain material, demonstrating that the disease associated prions generated in COs shared strain characteristics with those in humans. As the first and only in vitro model of human neurodegenerative disease that can faithfully reproduce different subtypes of prion disease, these findings support the use of the CO model for investigating human prion diseases and their subtypes.

Kinetics of the reduction of Creutzfeldt-Jakob disease prion seeding activity by steam sterilization support the use of validated 134°C programmes

BACKGROUND

Prions are renowned for their distinct resistance to chemical or physical inactivation, including steam sterilization. Impaired efficacy of inactivation poses a risk to patients for iatrogenic transmission of Creutzfeldt-Jakob disease (CJD) via contaminated surgical instruments.

AIMS

Most established prion inactivation methods were validated against scrapie agents, although those were found to be generally less thermostable than human prions. Thus, knowledge gaps regarding steam-sterilization kinetics of CJD prions should be filled and current guidelines reviewed accordingly.

METHODS

Prion inactivation through widely recommended steam sterilization at 134°C was assessed for several holding times by analysing the residual prion seeding activity using protein misfolding cyclic amplification (PMCA).

FINDINGS

Scrapie 263K was found to be the least thermoresistant prion strain showing no seeding activity after 1.5 min at 134°C, while variant CJD was the most stable one demonstrating some seeding activity even after 18 min of steam sterilization. Sporadic CJD subtype VV2 exhibited residual seeding activity after 3 min, but no detectable activity after 5 min at 134°C.

CONCLUSION

Validated steam sterilization for 5 min at 134°C as previously recommended for the routine reprocessing of surgical instruments in contact with high-risk tissues is able to substantially reduce the seeding activity of CJD agents, provided that no fixating chemical disinfection has been performed prior to sterilization and that thorough cleaning has reduced the protein load on the surface to less than 100 μg per instrument.

Combination of structure-based virtual screening, molecular docking and molecular dynamics approaches for the discovery of anti-prion fibril flavonoids

Prion diseases are a group of rare neurodegenerative diseases caused by the structural conversion of cellular prion into Scrapie prion resulting aggregated fibrils. Therapy of prion diseases has been developed for several decades, especially drug designs based on the structure of prion monomers. Unfortunately, none of the designed anti-prion drugs function well clinically. To fight against prion fibrils, a drug design based on the precise structure of mammalian prion fibrils is highly required. Fortunately, based on the advantage of newly advanced cryo-electron microscopy (cryo-EM) in the deconvolution of large complexes, three prion fibril structures were resolved in the last 2 years. Based on the cryo-EM solved prion fibril structures, we are able to find some molecules fighting against prion fibrils. Quercetin, one flavonoid molecule in the polyphenol group, has been found to disaggregate the prion fibrils in vitro. In this study, we performed the molecular docking and molecular dynamics simulation on quercetin-like molecules possessing pharmacological properties to evaluate the anti-prion ability of tested molecules. As a result, four quercetin-like molecules interact with prion fibril and decrease the β-strand content by converting some β-strands into loop and helical structures to disintegrate the existing fibril structure. The results of this study are significant in the treatment of prion diseases, and the approaches used in this study are applicable to other amyloid diseases.

Systematic Review of Clinical and Pathophysiological Features of Genetic Creutzfeldt-Jakob Disease Caused by a Val-to-Ile Mutation at Codon 180 in the Prion Protein Gene

Genetic Creutzfeldt-Jakob disease (gCJD) is a subtype of genetic prion diseases (gPrDs) caused by the accumulation of mutated pathological prion proteins (PrPSc). gCJD has a phenotypic similarity with sporadic CJD (sCJD). In Japan, gCJD with a Val to Ile substitution at codon 180 (V180I-gCJD) is the most frequent gPrD, while the mutation is extremely rare in countries other than Japan and Korea. In this article, we aim to review previously elucidated clinical and biochemical features of V180I-gCJD, expecting to advance the understanding of this unique subtype in gCJD. Compared to classical sCJD, specific clinical features of V180I-gCJD include older age at onset, a relatively slow progression of dementia, and a lower positivity for developing myoclonus, cerebellar, pyramidal signs, and visual disturbance. Diffuse edematous ribboning hyperintensity of the cerebral cortex, without occipital lobes in diffusion-weighted magnetic resonance imaging, is also specific. Laboratory data reveal the low positivity of PrPSc in the cerebrospinal fluid and periodic sharp wave complexes on an electroencephalogram. Most patients with V180I-gCJD have been reported to have no family history, probably due to the older age at onset, and clinical and biochemical features indicate the specific phenotype associated with the prion protein gene mutation.

Translatome profiling in fatal familial insomnia implicates TOR signaling in somatostatin neurons

Bauer and colleagues report that among the six neuron types studied, somatostatin neurons have an unexpectedly strong and similar response to two distinct genetic prion diseases before disease onset.

Selective neuronal vulnerability is common in neurodegenerative diseases but poorly understood. In genetic prion diseases, including fatal familial insomnia (FFI) and Creutzfeldt–Jakob disease (CJD), different mutations in the Prnp gene manifest as clinically and neuropathologically distinct diseases. Here we report with electroencephalography studies that theta waves are mildly increased in 21 mo old knock-in mice modeling FFI and CJD and that sleep is mildy affected in FFI mice. To define affected cell types, we analyzed cell type–specific translatomes from six neuron types of 9 mo old FFI and CJD mice. Somatostatin (SST) neurons responded the strongest in both diseases, with unexpectedly high overlap in genes and pathways. Functional analyses revealed up-regulation of neurodegenerative disease pathways and ribosome and mitochondria biogenesis, and down-regulation of synaptic function and small GTPase-mediated signaling in FFI, implicating down-regulation of mTOR signaling as the root of these changes. In contrast, responses in glutamatergic cerebellar neurons were disease-specific. The high similarity in SST neurons of FFI and CJD mice suggests that a common therapy may be beneficial for multiple genetic prion diseases.

Populations of Tau Conformers Drive Prion-like Strain Effects in Alzheimer's Disease and Related Dementias

Recent findings of diverse populations of prion-like conformers of misfolded tau protein expand the prion concept to Alzheimer's disease (AD) and monogenic frontotemporal lobar degeneration (FTLD)-MAPT P301L, and suggest that distinct strains of misfolded proteins drive the phenotypes and progression rates in many neurodegenerative diseases. Notable progress in the previous decades has generated many lines of proof arguing that yeast, fungal, and mammalian prions determine heritable as well as infectious traits. The extraordinary phenotypic diversity of human prion diseases arises from structurally distinct prion strains that target, at different progression speeds, variable brain structures and cells. Although human prion research presents beneficial lessons and methods to study the mechanism of strain diversity of protein-only pathogens, the fundamental molecular mechanism by which tau conformers are formed and replicate in diverse tauopathies is still poorly understood. In this review, we summarize up to date advances in identification of diverse tau conformers through biophysical and cellular experimental paradigms, and the impact of heterogeneity of pathological tau strains on personalized structure- and strain-specific therapeutic approaches in major tauopathies.

The First Evaluation of Proteinase K-Resistant Prion Protein (PrPSc) in Korean Appendix Specimens

Background and Objectives: Prion diseases are fatal neurodegenerative disorders caused by the abnormal proteinase K-resistant prion protein (PrP^Sc). Since variant Creutzfeldt–Jakob disease (CJD) was first reported in the United Kingdom (UK) in 1996, the occurrence of variant CJD has been reported in over 10 countries. To date, variant CJD has not been reported in Korea. However, the E211K somatic mutation in the prion protein gene (PRNP), which is related to bovine spongiform encephalopathy (BSE), was reported in Korean Holstein cattle, and atypical BSE, which is supposed to be sporadic BSE, has been occurring in many countries, including Japan and the USA. These results suggest that BSE may occur naturally in Korea. Thus, we performed a preemptive PrP^Sc test in appendix specimens to diagnose variant CJD in a Korean population. Materials and Methods: In the present study, we investigated CJD-related mutations and polymorphisms of the PRNP gene and carried out an examination on PrP^Sc in appendix specimens of Korean patients after appendectomy. Results: In all Korean appendix specimens tested, PrP^Sc bands were not detected. Conclusion: To the best of our knowledge, this was the first evaluation of PrP^Sc in Korean appendix specimens.

Sporadic Creutzfeldt-Jakob Disease in a Patient With Multiple Sclerosis: A Case Report

Sporadic Creutzfeldt-Jakob disease (CJD) is a rare neurodegenerative condition and a human prion disease. Rapid progressive dementia, myoclonus, visual disturbances, cerebellar signs, and pyramidal/extrapyramidal symptoms are observed in such patients. However, these are non-specific symptoms and can manifest in a variety of other conditions. The occurrence of sporadic CJD in a patient with multiple sclerosis (MS) is rare. This is the case of a 54-year-old man on natazulimab for MS who developed rapid neurocognitive changes along with visual changes, imbalance issues, and mood changes. Diagnosis of sporadic CJD (sCJD) was confirmed through clinical features, physical examination and electroencephalogram findings, cerebral spinal fluid analysis, and later magnetic resonance imaging findings. sCJD with MS being a rare phenomenon, its recognition requires a high index of suspicion, careful chronological evaluation of the patient’s symptoms, and relevant investigations that can aid in reaching the diagnosis.

Atypical Case of VV1 Creutzfeldt–Jakob Disease Subtype: Case Report

Creutzfeldt–Jakob disease (CJD) is a rare form of rapidly progressive, neurodegenerative disease that results from the misfolding and accumulation of an aberrant, disease-associated prion protein (PrPD). CJD affects 1–1.5 cases per million per year with the sporadic-type accounting for an estimated 85% of these cases. Sporadic CJD (sCJD) is further subdivided into five subtypes based on genetic polymorphisms; the rarest subtype, sCJDVV1, occurs at a rate of 1 case per one-hundredth million population per year. Clinical characteristics of the sCJDVV1 subtype have been reported to show, early age of onset (44 years), average disease duration of 21 months, absent PSWCs on electroencephalography (EEG), and MRI hyperintensities in the cerebral cortex with usual negative signal in the basal ganglia or thalamus. We present a case of the sCJDVV1 subtype with uncommon features. Contrary to current data on sCJDVV1, our patient presented with an unusual age at onset (61 years) and longer disease duration (32 months). The highly sensitive and specific real-time quaking-induced conversion (RT-QuIC) assay was negative. Presenting clinical symptoms included paranoid thoughts and agitation, rapidly progressive memory decline, prosopagnosia, and late development of myoclonus and mutism. Other findings showed positive antithyroid peroxidase antibodies (anti-TPO), and absent PSWCs on EEG. High-dose steroid therapy treatment was administered based on positive anti-TPO findings, which failed to elicit any improvement and the patient continued to decline. To our knowledge, only four cases with the sCJDVV1 subtype, including our patient, have been reported to have a negative result on RT-QuIC. This may suggest varied sensitivity across sCJD subtypes. However, given the rarity of our patient's subtype, and the relatively novel RT-QuIC, current data are based on a small number of cases and larger cohorts of confirmed VV1 cases with RT-QuIC testing need to be reported.

Proposal of new diagnostic criteria for fatal familial insomnia

Background

The understanding of fatal familial insomnia (FFI), a rare neurodegenerative autosomal dominant prion disease, has improved in recent years as more cases were reported. This work aimed to propose new diagnostic criteria for FFI with optimal sensitivity, specificity, and likelihood ratio.

Methods

An international group of experts was established and 128 genetically confirmed FFI cases and 281 non-FFI prion disease controls are enrolled in the validation process. The new criteria were proposed based on the following steps with two-round expert consultation: (1) Validation of the 2018 FFI criteria. (2) Diagnostic item selection according to statistical analysis and expert consensus. (3) Validation of the new criteria.

Results

The 2018 criteria for possible FFI had a sensitivity of 90.6%, a specificity of 83.3%, with a positive likelihood ratio (PLR) of 5.43, and a negative likelihood ratio (NLR) of 0.11; and the probable FFI criteria had a sensitivity of 83.6%, specificity of 92.9%, with a PLR of 11.77, and a NLR of 0.18. The new criteria included more specific and/or common clinical features, two exclusion items, and summarized a precise and flexible diagnostic hierarchy. The new criteria for possible FFI had therefore reached a better sensitivity and specificity (92.2% and 96.1%, respectively), a PLR of 23.64 and a NLR of 0.08, whereas the probable FFI criteria showed a sensitivity of 90.6%, a specificity of 98.2%, with a PLR of 50.33 and a NLR of 0.095.

Conclusions

We propose new clinical diagnostic criteria for FFI, for a better refining of the clinical hallmarks of the disease that ultimately would help an early recognition of FFI and a better differentiation from other prion diseases.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00415-022-11135-6.

Comprehensive clinical, radiological, pathological and biochemical analysis required to differentiate VV1 sporadic Creutzfeldt-Jakob disease from suspected variant CJD

Background

A diagnosis of variant Creutzfeldt-Jakob disease (vCJD), the zoonotic prion disease related to transmission of bovine spongiform encephalopathy, can carry enormous public health ramifications. Until recently, all vCJD clinical cases were confined to patients displaying methionine homozygosity (MM) at codon 129 of the prion protein gene (PRNP). The recent diagnosis of vCJD in a patient heterozygous (MV) at codon 129 reignited concerns regarding a second wave of vCJD cases, with the possibility of phenotypic divergence from MM vCJD and greater overlap with sporadic CJD (sCJD) molecular subtypes.

Method and results

We present a case of CJD with clinico-epidemiological and radiological characteristics creating initial concerns for vCJD. Thorough case evaluation, including data provided by genetic testing, autopsy and neuropathological histological analyses, provided a definitive diagnosis of the rare VV1 molecular subtype of sCJD.

Conclusion

Distinguishing vCJD from sCJD is of vital public health importance and potentially more problematic with the development of non-MM vCJD cases. The patient described herein demonstrates that in addition to the clinico-epidemiological profile, combined supplementary pathological, biochemical and critical radiological analysis may be necessary for confident discrimination of sCJD, especially rare sub-types, from vCJD.

Diagnostic accuracy of cerebrospinal fluid biomarkers in genetic prion diseases

Genetic prion diseases are a rare and diverse group of fatal neurodegenerative disorders caused by pathogenic sequence variations in the prion protein gene, PRNP. Data on CSF biomarkers in patients with genetic prion diseases are limited and conflicting results have been reported for unclear reasons.

Here, we aimed to analyse the diagnostic accuracy of CSF biomarkers currently used in prion clinical diagnosis in 302 symptomatic genetic prion disease cases from 11 prion diagnostic centres, encompassing a total of 36 different pathogenic sequence variations within the open reading frame of PRNP.

CSF samples were assessed for the surrogate markers of neurodegeneration, 14-3-3 protein (14-3-3), total-tau protein (t-tau) and α-synuclein and for prion seeding activity through the real-time quaking-induced conversion assay. Biomarker results were compared with those obtained in healthy and neurological controls. For the most prevalent PRNP pathogenic sequence variations, biomarker accuracy and associations between biomarkers, demographic and genetic determinants were assessed. Additionally, the prognostic value of biomarkers for predicting total disease duration from symptom onset to death was investigated.

High sensitivity of the four biomarkers was detected for genetic Creutzfeldt–Jakob disease associated with the E200K and V210I mutations, but low sensitivity was observed for mutations associated with Gerstmann–Sträussler–Scheinker syndrome and fatal familial insomnia. All biomarkers showed good to excellent specificity using the standard cut-offs often used for sporadic Creutzfeldt–Jakob disease. In genetic prion diseases related to octapeptide repeat insertions, the biomarker sensitivity correlated with the number of repeats. New genetic prion disease-specific cut-offs for 14-3-3, t-tau and α-synuclein were calculated. Disease duration in genetic Creutzfeldt–Jakob disease-E200K, Gerstmann–Sträussler–Scheinker-P102L and fatal familial insomnia was highly dependent on PRNP codon 129 MV polymorphism and was significantly associated with biomarker levels.

In a large cohort of genetic prion diseases, the simultaneous analysis of CSF prion disease biomarkers allowed the determination of new mutation-specific cut-offs improving the discrimination of genetic prion disease cases and unveiled genetic prion disease-specific associations with disease duration.

CSF biomarkers for prion diseases

Recently, clinical trials of human prion disease (HPD) treatments have begun in many countries, and the therapeutic window of these trials focuses mainly on the early stage of the disease. Furthermore, few studies have examined the role of biomarkers at the early stage. According to the World Health Organization, the clinical diagnostic criteria for HPDs include clinical findings, cerebrospinal fluid (CSF) protein markers, and electroencephalography (EEG). In contrast, the UK and European clinical diagnostic criteria include a combination of clinical findings, 14-3-3 protein in the CSF, magnetic resonance imaging-diffusion-weighted imaging (MRI-DWI), and EEG. Moreover, recent advancements in laboratory testing and MRI-DWI have improved the accuracy of diagnostics used for prion diseases. However, according to MRI-DWI data, patients with rapidly progressing dementia are sometimes misdiagnosed with HPD due to the high-intensity areas detected in their brains. Thus, analyzing the CSF biomarkers is critical to diagnose accurately different diseases. CSF biomarkers are investigated using a biochemical approach or the protein amplification methods that utilize the unique properties of prion proteins and the ability of PrP^Sc to induce a conformational change. The biochemical markers include the 14-3-3 and total tau proteins of the CSF. In contrast, the protein amplification methods include the protein misfolding cyclic amplification assay and real-time quaking-induced conversion (RT-QuIC) assay. The RT-QuIC analysis of the CSF has been proved to be a highly sensitive and specific test for identifying sporadic HPD forms; for this reason, it was included in the diagnostic criteria.

Cell biology of prion strains in vivo and in vitro

The properties of infectious prions and the pathology of the diseases they cause are dependent upon the unique conformation of each prion strain. How the pathology of prion disease correlates with different strains and genetic backgrounds has been investigated via in vivo assays, but how interactions between specific prion strains and cell types contribute to the pathology of prion disease has been dissected more effectively using in vitro cell lines. Observations made through in vivo and in vitro assays have informed each other with regard to not only how genetic variation influences prion properties, but also how infectious prions are taken up by cells, modified by cellular processes and propagated, and the cellular components they rely on for persistent infection. These studies suggest that persistent cellular infection results from a balance between prion propagation and degradation. This balance may be shifted depending upon how different cell lines process infectious prions, potentially altering prion stability, and how fast they can be transported to the lysosome. Thus, in vitro studies have given us a deeper understanding of the interactions between different prions and cell types and how they may influence prion disease phenotypes in vivo.

Creutzfeldt-Jakob Disease Following Kidney Transplantation

Neurologic complications after kidney transplantation are frequent and related to immunosuppressive therapy and vintage dialysis time, including comorbidities such as diabetes, hypertension, and cardiovascular diseases. Creutzfeldt-Jakob disease (CJD) is a very rare and rapidly fatal neurodegenerative disorder. Kidney transplant recipients present with mixed and complex neuropsychiatric manifestations, which makes diagnosis challenging. This case highlights the importance of enhancing awareness of the clinical presentation and timely diagnosis of this rare, fatal neurodegenerative disorder.

Differential Accumulation of Misfolded Prion Strains in Natural Hosts of Prion Diseases

Prion diseases, also known as transmissible spongiform encephalopathies (TSEs), are a group of neurodegenerative protein misfolding diseases that invariably cause death. TSEs occur when the endogenous cellular prion protein (PrP^C) misfolds to form the pathological prion protein (PrP^Sc), which templates further conversion of PrP^C to PrP^Sc, accumulates, and initiates a cascade of pathologic processes in cells and tissues. Different strains of prion disease within a species are thought to arise from the differential misfolding of the prion protein and have different clinical phenotypes. Different strains of prion disease may also result in differential accumulation of PrP^Sc in brain regions and tissues of natural hosts. Here, we review differential accumulation that occurs in the retinal ganglion cells, cerebellar cortex and white matter, and plexuses of the enteric nervous system in cattle with bovine spongiform encephalopathy, sheep and goats with scrapie, cervids with chronic wasting disease, and humans with prion diseases. By characterizing TSEs in their natural host, we can better understand the pathogenesis of different prion strains. This information is valuable in the pursuit of evaluating and discovering potential biomarkers and therapeutics for prion diseases.

Homozygous R136S mutation in PRNP gene causes inherited early onset prion disease

BACKGROUND

More than 40 pathogenic heterozygous PRNP mutations causing inherited prion diseases have been identified to date. Recessive inherited prion disease has not been described to date.

METHODS

We describe the clinical and neuropathological data of inherited early-onset prion disease caused by the rare PRNP homozygous mutation R136S. In vitro PrPSc propagation studies were performed using recombinant-adapted protein misfolding cyclic amplification technique. Brain material from two R136S homozygous patients was intracranially inoculated in TgMet129 and TgVal129 transgenic mice to assess the transmissibility of this rare inherited form of prion disease.

RESULTS

The index case presented symptoms of early-onset dementia beginning at the age of 49 and died at the age of 53. Neuropathological evaluation of the proband revealed abundant multicentric PrP plaques and Western blotting revealed a ~ 8 kDa protease-resistant, unglycosylated PrPSc fragment, consistent with a Gerstmann-Sträussler-Scheinker phenotype. Her youngest sibling suffered from progressive cognitive decline, motor impairment, and myoclonus with onset in her late 30s and died at the age of 48. Genetic analysis revealed the presence of the R136S mutation in homozygosis in the two affected subjects linked to homozygous methionine at codon 129. One sibling carrying the heterozygous R136S mutation, linked to homozygous methionine at codon 129, is still asymptomatic at the age of 74. The inoculation of human brain homogenates from our index case and an independent case from a Portuguese family with the same mutation in transgenic mice expressing human PrP and in vitro propagation of PrPSc studies failed to show disease transmissibility.

CONCLUSION

In conclusion, biallelic R136S substitution is a rare variant that produces inherited early-onset human prion disease with a Gerstmann-Sträussler-Scheinker neuropathological and molecular signature. Even if the R136S variant is predicted to be "probably damaging", heterozygous carriers are protected, at least from an early onset providing evidence for a potentially recessive pattern of inheritance in human prion diseases.

Human Prion Disorders: Review of the Current Literature and a Twenty-Year Experience of the National Surveillance Center in the Czech Republic

Human prion disorders (transmissible spongiform encephalopathies, TSEs) are unique, progressive, and fatal neurodegenerative diseases caused by aggregation of misfolded prion protein in neuronal tissue. Due to the potential transmission, human TSEs are under active surveillance in a majority of countries; in the Czech Republic data are centralized at the National surveillance center (NRL) which has a clinical and a neuropathological subdivision. The aim of our article is to review current knowledge about human TSEs and summarize the experience of active surveillance of human prion diseases in the Czech Republic during the last 20 years. Possible or probable TSEs undergo a mandatory autopsy using a standardized protocol. From 2001 to 2020, 305 cases of sporadic and genetic TSEs including 8 rare cases of Gerstmann-Sträussler-Scheinker syndrome (GSS) were confirmed. Additionally, in the Czech Republic, brain samples from all corneal donors have been tested by the NRL immunology laboratory to increase the safety of corneal transplants since January 2007. All tested 6590 corneal donor brain tissue samples were negative for prion protein deposits. Moreover, the routine use of diagnostic criteria including biomarkers are robust enough, and not even the COVID-19 pandemic has negatively impacted TSEs surveillance in the Czech Republic.

Genetic Creutzfeldt-Jakob disease shows fatal family insomnia phenotype

We report a case of genetic Creutzfeldt-Jakob disease (gCJD), which has a clinical phenotype that is highly similar to Fatal Family Insomnia (FFI) and has a triad of Wernicke-Korsakoff syndrome (WKs) at the developmental stage of the disease. The 51-year-old male complained of sleep disorder and imbalance who had visited five different hospitals before diagnosed. A neurological examination revealed a triad of symptoms characteristic for WKs such as gaze paresis, ataxia of limbs and trunk, and memory disturbances. The disturbances increased during the course of the disease, which led to the death of the patient 18 months after the appearance of the signs. Although the patient show negative in brain magnetic resonance imaging (MRI) and 14-3-3 protein of cerebrospinal fluid (CSF), he was finally diagnosed with gCJD disease by the human prion protein (PRNP) gene mutations.

Loss of PIKfyve drives the spongiform degeneration in prion diseases

Brain‐matter vacuolation is a defining trait of all prion diseases, yet its cause is unknown. Here, we report that prion infection and prion‐mimetic antibodies deplete the phosphoinositide kinase PIKfyve—which controls endolysosomal maturation—from mouse brains, cultured cells, organotypic brain slices, and brains of Creutzfeldt‐Jakob disease victims. We found that PIKfyve is acylated by the acyltransferases zDHHC9 and zDHHC21, whose juxtavesicular topology is disturbed by prion infection, resulting in PIKfyve deacylation and rapid degradation, as well as endolysosomal hypertrophy and activation of TFEB‐dependent lysosomal enzymes. A protracted unfolded protein response (UPR), typical of prion diseases, also induced PIKfyve deacylation and degradation. Conversely, UPR antagonists restored PIKfyve levels in prion‐infected cells. Overexpression of zDHHC9 and zDHHC21, administration of the antiprion polythiophene LIN5044, or supplementation with the PIKfyve reaction product PI(3,5)P₂ suppressed prion‐induced vacuolation and restored lysosomal homeostasis. Thus, PIKfyve emerges as a central mediator of vacuolation and neurotoxicity in prion diseases.

Structurally distinct external solvent-exposed domains drive replication of major human prions

There is a limited understanding of structural attributes that encode the iatrogenic transmissibility and various phenotypes of prions causing the most common human prion disease, sporadic Creutzfeldt-Jakob disease (sCJD). Here we report the detailed structural differences between major sCJD MM1, MM2, and VV2 prions determined with two complementary synchrotron hydroxyl radical footprinting techniques—mass spectrometry (MS) and conformation dependent immunoassay (CDI) with a panel of Europium-labeled antibodies. Both approaches clearly demonstrate that the phenotypically distant prions differ in a major way with regard to their structural organization, and synchrotron-generated hydroxyl radicals progressively inhibit their seeding potency in a strain and structure-specific manner. Moreover, the seeding rate of sCJD prions is primarily determined by strain-specific structural organization of solvent-exposed external domains of human prion particles that control the seeding activity. Structural characteristics of human prion strains suggest that subtle changes in the organization of surface domains play a critical role as a determinant of human prion infectivity, propagation rate, and targeting of specific brain structures.

Sporadic human prion diseases are conceivably the most heterogenous neurodegenerative disorders and a growing body of research indicates that they are caused by distinct strains of prions. By parallel monitoring their replication potency and progressive hydroxyl radical modification of amino acid side chains during synchrotron irradiation, we identified major differences in the structural organization that correlate with distinct inactivation susceptibility of a given human prion strain. Furthermore, our data demonstrated, for the first time, that seeding activity of different strains of infectious brain-derived human prions is primarily function of distinct solvent-exposed structural domains, and implicate them in the initial binding of cellular isoform of prion protein (PrPC) as a critical step in human prion replication and infectivity.

TREM2 expression in the brain and biological fluids in prion diseases

Triggering receptor expressed on myeloid cells 2 (TREM2) is an innate immune cell surface receptor that regulates microglial function and is involved in the pathophysiology of several neurodegenerative diseases. Its soluble form (sTREM2) results from shedding of the TREM2 ectodomain. The role of TREM2 in prion diseases, a group of rapidly progressive dementias remains to be elucidated. In the present study, we analysed the expression of TREM2 and its main sheddase ADAM10 in the brain of sporadic Creutzfeldt-Jakob disease (sCJD) patients and evaluated the role of CSF and plasma sTREM2 as a potential diagnostic marker of prion disease. Our data indicate that, compared to controls, TREM2 is increased in sCJD patient brains at the mRNA and protein levels in a regional and subtype dependent fashion, and expressed in a subpopulation of microglia. In contrast, ADAM10 is increased at the protein, but not the mRNA level, with a restricted neuronal expression. Elevated CSF sTREM2 is found in sCJD, genetic CJD with mutations E200K and V210I in the prion protein gene (PRNP), and iatrogenic CJD, as compared to healthy controls (HC) (AUC = 0.78–0.90) and neurological controls (AUC = 0.73–0.85), while CSF sTREM2 is unchanged in fatal familial insomnia. sTREM2 in the CSF of cases with Alzheimer’s disease, and multiple sclerosis was not significantly altered in our series. CSF sTREM2 concentrations in sCJD are PRNP codon 129 and subtype-related, correlate with CSF 14-3-3 positivity, total-tau and YKL-40, and increase with disease progression. In plasma, sTREM2 is increased in sCJD compared with HC (AUC = 0.80), displaying positive correlations with plasma total-tau, neurofilament light, and YKL-40. We conclude that comparative study of TREM2 in brain and biological fluids of prion diseases reveals TREM2 to be altered in human prion diseases with a potential value in target engagement, patient stratification, and disease monitoring.

Further Characterization of Glycoform-Selective Prions of Variably Protease-Sensitive Prionopathy

Prion is an infectious protein (PrP^Sc) that is derived from a cellular glycoprotein (PrP^C) through a conformational transition and associated with a group of prion diseases in animals and humans. Characterization of proteinase K (PK)-resistant PrP^Sc by western blotting has been critical to diagnosis and understanding of prion diseases including Creutzfeldt-Jakob disease (CJD) and Gerstmann-Sträussler-Scheinker (GSS) disease in humans. However, formation as well as biochemical and biological properties of the glycoform-selective PrP^Sc in variably protease-sensitive prionopathy (VPSPr) remain poorly understood. Here we reveal that formation of the ladder-like PrP^Sc in VPSPr is a PK-dependent two-step process, which is enhanced by basic pH. Two sets of PrP^Sc fragments can be identified with antibodies directed against an intermediate or a C-terminal domain of the protein. Moreover, antibodies directed against specific PrP glycoforms reveal faster electrophoretic migrations of PrP fragments mono-glycosylated at residue 181 and 197 in VPSPr than those in sporadic CJD (sCJD). Finally, RT-QuIC assay indicates that PrP^Sc-seeding activity is lower and its lag time is longer in VPSPr than in sCJD. Our results suggest that the glycoform-selective PrP^Sc in VPSPr is associated with altered glycosylation, resulting in different PK-truncation and aggregation seeding activity compared to PrP^Sc in sCJD.

Diagnostic and prognostic value of plasma neurofilament light and total-tau in sporadic Creutzfeldt-Jakob disease

BACKGROUND

Blood neurofilament light (Nfl) and total-tau (t-tau) have been described to be increased in several neurological conditions, including prion diseases and other neurodegenerative dementias. Here, we aim to determine the accuracy of plasma Nfl and t-tau in the differential diagnosis of neurodegenerative dementias and their potential value as prognostic markers of disease severity.

METHODS

Plasma Nfl and t-tau were measured in healthy controls (HC, n = 70), non-neurodegenerative neurological disease with (NND-Dem, n = 17) and without dementia syndrome (NND, n = 26), Alzheimer's disease (AD, n = 44), Creutzfeldt-Jakob disease (CJD, n = 83), dementia with Lewy bodies/Parkinson's disease with dementia (DLB/PDD, n = 35), frontotemporal dementia (FTD, n = 12), and vascular dementia (VaD, n = 22). Biomarker diagnostic accuracies and cutoff points for the diagnosis of CJD were calculated, and associations between Nfl and t-tau concentrations with other fluid biomarkers, demographic, genetic, and clinical data in CJD cases were assessed. Additionally, the value of Nfl and t-tau predicting disease survival in CJD was evaluated.

RESULTS

Among diagnostic groups, highest plasma Nfl and t-tau concentrations were detected in CJD (fold changes of 38 and 18, respectively, compared to HC). Elevated t-tau was able to differentiate CJD from all other groups, whereas elevated Nfl concentrations were also detected in NND-Dem, AD, DLB/PDD, FTD, and VaD compared to HC. Both biomarkers discriminated CJD from non-CJD dementias with an AUC of 0.93. In CJD, plasma t-tau, but not Nfl, was associated with PRNP codon 129 genotype and CJD subtype. Positive correlations were observed between plasma Nfl and t-tau concentrations, as well as between plasma and CSF concentrations of both biomarkers (p < 0.001). Nfl was increased in rapidly progressive AD (rpAD) compared to slow progressive AD (spAD) and associated to Mini-Mental State Examination results. However, Nfl displayed higher accuracy than t-tau discriminating CJD from rpAD and spAD. Finally, plasma t-tau, but not plasma Nfl, was significantly associated with disease duration, offering a moderate survival prediction capacity.

CONCLUSIONS

Plasma Nfl and t-tau are useful complementary biomarkers for the differential diagnosis of CJD. Additionally, plasma t-tau emerges as a potential prognostic marker of disease duration.

Amyloid pathology arrangements in Alzheimer's disease brains modulate in vivo seeding capability

Amyloid-β (Aβ) misfolding is one of the hallmark pathological features of Alzheimer's disease (AD). AD can manifest with diverse symptomatology including variable rates of cognitive decline, duration of clinical disease, and other detrimental changes. Several reports suggest that conformational diversity in misfolded Aβ is a leading factor for clinical variability in AD, analogous to what it has been described for prion strains in prion diseases. Notably, prion strains generate diverse patterns of misfolded protein deposition in the brains of affected individuals. Here, we tested the in vivo prion-like transmission features of four AD brains displaying particular patterns of amyloidosis. AD brains induced different phenotypes in recipient mice, as evaluated by their specific seeding activity, as well as the total amount of Aβ deposited surrounding vascular structures and the reactivity of amyloid pathology to thioflavin S. Our results support the notion that AD-subtypes are encoded in disease-associated Aβ. Further research exploring whether AD include a spectrum of different clinical conditions or syndromes may pave the way to personalized diagnosis and treatments.

Two distinct conformers of PrPD type 1 of sporadic Creutzfeldt-Jakob disease with codon 129VV genotype faithfully propagate in vivo

Current classifications of sporadic Creutzfeldt–Jakob disease (sCJD) identify five subtypes associated with different disease phenotypes. Most of these histopathological phenotypes (histotypes) co-distribute with distinct pairings of methionine (M)/valine (V) genotypes at codon 129 of the prion protein (PrP) gene and the type (1 or 2) of the disease-associated PrP (PrP^D). Types 1 and 2 are defined by the molecular mass (~ 21 kDa and ~ 19 kDa, respectively) of the unglycosylated isoform of the proteinase K-resistant PrP^D (resPrP^D). We recently reported that the sCJDVV1 subtype (129VV homozygosity paired with PrP^D type 1, T1) shows an electrophoretic profile where the resPrP^D unglycosylated isoform is characterized by either one of two single bands of ~ 20 kDa (T1²⁰) and ~ 21 kDa (T1²¹), or a doublet of ~ 21–20 kDa (T1²¹⁻²⁰). We also showed that T1²⁰ and T1²¹ in sCJDVV have different conformational features but are associated with indistinguishable histotypes. The presence of three distinct molecular profiles of T1 is unique and raises the issue as to whether T1²⁰ and T1²¹ represent distinct prion strains. To answer this question, brain homogenates from sCJDVV cases harboring each of the three resPrP^D profiles, were inoculated to transgenic (Tg) mice expressing the human PrP-129M or PrP-129V genotypes. We found that T1²⁰ and T1²¹ were faithfully replicated in Tg129V mice. Electrophoretic profile and incubation period of mice challenged with T1²¹⁻²⁰ resembled those of mice inoculated with T1²¹ and T1²⁰, respectively. As in sCJDVV1, Tg129V mice challenged with T1²¹ and T1²⁰ generated virtually undistinguishable histotypes. In Tg129M mice, T1²¹ was not replicated while T1²⁰ and T1²¹⁻²⁰ generated a ~ 21–20  kDa doublet after lengthier incubation periods. On second passage, Tg129M mice incubation periods and regional PrP accumulation significantly differed in T1²⁰ and T1²¹⁻²⁰ challenged mice. Combined, these data indicate that T1²¹ and T1²⁰ resPrP^D represent distinct human prion strains associated with partially overlapping histotypes.

Distribution of microRNA profiles in pre-clinical and clinical forms of murine and human prion disease

Prion diseases are distinguished by long pre-clinical incubation periods during which prions actively propagate in the brain and cause neurodegeneration. In the pre-clinical stage, we hypothesize that upon prion infection, transcriptional changes occur that can lead to early neurodegeneration. A longitudinal analysis of miRNAs in pre-clinical and clinical forms of murine prion disease demonstrated dynamic expression changes during disease progression in the affected thalamus region and serum. Serum samples at each timepoint were collected whereby extracellular vesicles (EVs) were isolated and used to identify blood-based biomarkers reflective of pathology in the brain. Differentially expressed EV miRNAs were validated in human clinical samples from patients with human sporadic Creutzfeldt-Jakob disease (sCJD), with the molecular subtype at codon 129 either methionine-methionine (MM, n = 14) or valine-valine (VV, n = 12) compared to controls (n = 20). EV miRNA biomarkers associated with prion infection predicted sCJD with an AUC of 0.800 (85% sensitivity and 66.7% specificity) in a second independent validation cohort (n = 26) of sCJD and control patients with MM or VV subtype. This study discovered clinically relevant miRNAs that benefit diagnostic development to detect prion-related diseases and therapeutic development to inhibit prion infectivity.

Cheng et al. present differentially expressed extracellular vesicle miRNAs in human clinical samples from patients who suffer from sporadic Creutzfeldt-Jakob disease. This study identifies biomarkers that can be used to detect prion-related diseases, providing insights into drug development for inhibiting prion infectivity.

Creutzfeldt-Jakob Disease May Present Early With Unusual Bulbar Predominance

INTRODUCTION

Creutzfeldt-Jakob disease (CJD) is a prion protein disorder of significant consequence and currently incurable. Diagnosis can be challenging early in the disease course. CJD can present in many ways but often fits a pattern of cognitive problems, cerebellar disturbance, behavioral/psychological changes, and perhaps myoclonus.

CASE REPORT

We herein present the case of a 69-year-old White male with subacute progressive bulbar and limb weakness over ten weeks period. Early on, he was diagnosed with amyotrophic lateral sclerosis versus autoimmune-related bulbar neuropathy and treated as such. However, he continued to deteriorate clinically that prompted another admission, upon readmission, his cerebrospinal fluid RTQuick and 14-3-3 from the National Prion Disease Pathology Surveillance Center (NPDPSC) did eventually return positive. Hence he was diagnosed with CJD.

CONCLUSIONS

CJD may present with progressive bulbar symptoms similar to acute inflammatory demyelinating polyradiculoneuropathy (MF variant), motor neuron disease, or autoimmune brainstem encephalitis. It becomes even higher on the differentials especially with no response to immunotherapy.

Subtype Diagnosis of Sporadic Creutzfeldt-Jakob Disease with Diffusion Magnetic Resonance Imaging

OBJECTIVE

Sporadic Creutzfeldt-Jakob disease (sCJD) comprises several subtypes as defined by genetic and prion protein characteristics, which are associated with distinct clinical and pathological phenotypes. To date, no clinical test can reliably diagnose the subtype. We established two procedures for the antemortem diagnosis of sCJD subtype using diffusion magnetic resonance imaging (MRI).

METHODS

MRI of 1,458 patients referred to the National Prion Disease Pathology Surveillance Center were collected through its consultation service. One neuroradiologist blind to the diagnosis scored 12 brain regions and generated a lesion profile for each MRI scan. We selected 487 patients with autopsy-confirmed diagnosis of "pure" sCJD subtype and at least one positive diffusion MRI examination. We designed and tested two data-driven procedures for subtype diagnosis: the first procedure-prion subtype classification algorithm with MRI (PriSCA_MRI)-uses only MRI examinations; the second-PriSCA_MRI + Gen-includes knowledge of the prion protein codon 129 genotype, a major determinant of sCJD subtypes. Both procedures were tested on the first MRI and the last MRI follow-up.

RESULTS

PriSCA_MRI classified the 3 most prevalent subtypes with 82% accuracy. PriSCA_MRI + Gen raised the accuracy to 89% and identified all subtypes. Individually, the 2 most prevalent sCJD subtypes, MM1 and VV2, were diagnosed with sensitivities up to 95 and 97%, respectively. The performances of both procedures did not change in 168 patients with longitudinal MRI studies when the last examination was used.

INTERPRETATION

This study provides the first practical algorithms for antemortem diagnosis of sCJD subtypes. MRI diagnosis of subtype is likely to be attainable at early disease stages to prognosticate clinical course and design future therapeutic trials. ANN NEUROL 2021;89:560-572.