Sporadic CJD Research Articles

Tau, prions and Aβ: the triad of neurodegeneration.

This article highlights the features that connect prion diseases with other cerebral amyloidoses and how these relate to neurodegeneration, with focus on tau phosphorylation. It also discusses similarities between prion disease and Alzheimer’s disease: mechanisms of amyloid formation, neurotoxicity, pathways involved in triggering tau phosphorylation, links to cell cycle pathways and neuronal apoptosis. We review previous evidence of prion diseases triggering hyperphosphorylation of tau, and complement these findings with cases from our collection of genetic, sporadic and transmitted forms of prion diseases. This includes the novel finding that tau phosphorylation consistently occurs in sporadic CJD, in the absence of amyloid plaques.Electronic supplementary materialThe online version of this article (doi:10.1007/s00401-010-0691-0) contains supplementary material, which is available to authorized users.

The Octarepeat Region of the Prion Protein Is Conformationally Altered in PrPSc

BackgroundPrion diseases are fatal neurodegenerative disorders characterized by misfolding and aggregation of the normal prion protein PrPC. Little is known about the details of the structural rearrangement of physiological PrPC into a still-elusive disease-associated conformation termed PrPSc. Increasing evidence suggests that the amino-terminal octapeptide sequences of PrP (huPrP, residues 59–89), though not essential, play a role in modulating prion replication and disease presentation.Methodology/Principal FindingsHere, we report that trypsin digestion of PrPSc from variant and sporadic human CJD results in a disease-specific trypsin-resistant PrPSc fragment including amino acids ∼49–231, thus preserving important epitopes such as the octapeptide domain for biochemical examination. Our immunodetection analyses reveal that several epitopes buried in this region of PrPSc are exposed in PrPC.Conclusions/SignificanceWe conclude that the octapeptide region undergoes a previously unrecognized conformational transition in the formation of PrPSc. This phenomenon may be relevant to the mechanism by which the amino terminus of PrPC participates in PrPSc conversion, and may also be exploited for diagnostic purposes.

Agent-specific Shadoo Responses in Transmissible Encephalopathies

Transmissible spongiform encephalopathies (TSE) are neurodegenerative diseases caused by an infectious agent with viral properties. Host prion protein (PrP), a marker of late stage TSE pathology, is linked to a similar protein called Shadoo (Sho). Sho is reduced in mice infected with the RML scrapie agent, but has not been investigated in other TSEs. Although PrP is required for infection by TSE agents, it is not known if Sho is similarly required. Presumably Sho protects cells from toxic effects of misfolded PrP. We compared Sho and PrP changes after infection by very distinct TSE agents including sporadic CJD, Asiatic CJD, New Guinea kuru, vCJD (the UK epidemic bovine agent) and 22L sheep scrapie, all passaged in standard mice. We found that Sho reductions were agent-specific. Variable Sho reductions in standard mice could be partly explained by agent-specific differences in regional neuropathology. However, Sho did not follow PrP misfolding in any quantitative or consistent way. Tga20 mice with high murine PrP levels revealed additional agent-specific differences. Sho was unaffected by Asiatic CJD yet was markedly reduced by the kuru agent in Tga20 mice; in standard mice both agents induced the same Sho reductions. Analyses of neural GT1 cells demonstrated that Sho was not essential for TSE infections. Furthermore, because all infected GT1 cells appeared as healthy as uninfected controls, Sho was not needed to protect infected cells from their "toxic" burden of abundant abnormal PrP and intracellular amyloid.

Prion disease

Human prion diseases are classified into 3 categories according to etiologies: idiopathic of unknown cause, acquired of infectious origin, and genetic by PRNP mutation. The surveillance committee have analyzed 2,494 cases and identified 1,402 as prion diseases. Most of them are idiopathic, namely sporadic CJD (77%) with less genetic and acquired prion diseases (17% and 5%, respectively). The number of patients identified by the surveillance committee in these years is about 120 which are less than the number of annual death of prion disease. The difference might be due to partly the fact our surveillance need the consent from patients' family and is not complete. The mean age at onset of prion disease is late 60s while the range is fairly wide. Brain MRIs and increase of CSF 14-3-3 and tau protein levels are very characteristic. Classical sporadic CJD could show completely normal T1WI with patchy high signals in the cerebral cortex and basal ganglia on DWI. In Japan, classical sporadic CJD (MM1) is most popular but there are some rare atypical subtypes. Among them, MM2-thalamic CJD is hardest to diagnose because it shows no high intensity signals on DWI, in addition to frequent absence of CSF and EEG characteristics. In this case, CBF decrease in the thalamus on SPECT is very helpful. Genetic prion diseases in Japan are quite distinct from those in Europe. V180I and M232R mutations are unique to Japan and show sporadic CJD phenotype. Dura graft-associated CJD (dCJD) are composed of 67% of classical sporadic CJD phenotype and 33% of atypical phenotype showing slower progression with amyloid plaques. Trace-back experiments suggested the PrPsc of the atypical dCJD was likely to be modified from infection of abnormal VV2 protein. Although there are some atypical forms of prion diseases as mentioned above, almost all prion cases could be diagnosed with EEG, MRI, genetic test, CSF test and SPECT. We also have some incidents in which brain surgery was done before the diagnosis of prion disease and many other patients were operated using the same operating instruments before their sterilization against prion disease had been done. The explanation of possibility of prion disease infection to the patients and their follow-up was started by the incident committee. It is very important for all the nations to cooperate with each other in order to overcome this intractable disease.

A 16-year old male with cortical blindness and focal motor seizures

A 16-year old male with cortical blindness and focal motor seizures

Creutzfeldt‐Jakob disease with an M232R substitution: report of a patient showing slowly progressive disease with abundant plaque‐like PrP deposits in the cerebellum

Patients with genetic Creutzfeldt-Jakob disease in which arginine is substituted for methionine at codon 232 (M232R) of the prion protein gene (CJD232) have been described in Japan, and a recent study has revealed the presence of two clinical phenotypes: a rapidly progressive type (rapid-type) and a slowly progressive type (slow-type). Although the former is known to show pathologic features similar to those of classical CJD, the neuropathology of the latter still remains unclear. We report the autopsy findings of slow-type CJD232 of 37 months' duration in a 73-year-old man who had methionine homozygosity at codon 129 of the prion protein gene (129MM). His initial symptoms included agraphia and memory disturbance, followed by relatively slowly progressive dementia. Myoclonus and akinetic mutism became evident 5 and 23 months after disease onset, respectively. The electroencephalogram revealed periodic sharp wave complexes at 7 months before death. The neuropathologic features were partly reminiscent of those of MM2-cortical-type sporadic CJD, showing spongiform change of the large confluent vacuole type, neuronal loss with gliosis, and coarse, perivacuolar prion protein deposits, which were later shown to consist of protease-resistant type 2 prion protein, in the cerebral cortex and striatum. It was of considerable interest that not only was the medial thalamus severely involved, but also that the cerebellar cortex showed loss of Purkinje cells and abundant plaque-like prion protein deposits. These findings are not a feature of MM2-cortical-type sporadic CJD. Whether or not the M232R substitution, in combination with the genetic polymorphism and the molecular type of pathological prion protein, really participates in the development of CJD232 and its different phenotypes awaits further studies.

An autopsied case of panencephalopathic‐type Creutzfeldt‐Jakob disease with mutation in the prion protein gene at codon 232 and type 1 prion protein

In this study, we describe the clinicopathologic findings in a 68-year-old man with panencephalopathic-type CJD with a substitution from methionine to arginine at codon 232 (M232R) in the prion protein (PrP) gene and type 1 PrP. Initial symptoms of the patient were a rapidly progressive memory disturbance and disorientation. The patient showed myoclonus and periodic sharp-wave complexes on electroencephalogram in the early stages of disease. Diffusion-weighted MRI along with the presence of both neuron-specific enolase and 14-3-3 protein in the CSF showed similarities to classic-type sporadic CJD. The patient reached the akinetic mutism state 2 months following the onset of symptoms and died after 13 months. Neuropathologic examination revealed panencephalopathic-type CJD pathology including widespread neuron loss with severe hypertrophic astrocytosis and status spongiosus in the cerebral gray matter, particularly in the neocortex. Cerebral white matter and the cerebellum also showed severe involvement. Immunohistochemical staining for PrP showed diffuse gray matter staining, indicating synaptic-type PrP deposition without plaque-type. Two different clinical phenotypes of M232R CJD were recognized despite the presence of the same PrP genotype, and the present case is speculated to correspond to the rapid-type.

Spatial Correlations between the Vacuolation, Prion Protein (PrPsc) Deposits and the Cerebral Blood Vessels in Sporadic Creutzfeldt-Jakob Disease

In the variant form of Creutzfeldt-Jakob disease (vCJD), 'florid' deposits of the protease resistant form of prion protein (PrP(sc)) were aggregated around the cerebral blood vessels suggesting the possibility that prions may spread into the brain via the cerebral microcirculation. The objective of the present study was to determine whether the pathology was spatially related to blood vessels in cases of sporadic CJD (sCJD), a disease without an iatrogenic etiology, and therefore, less likely to be caused by hematogenous spread. Hence, the spatial correlations between the vacuolation ('spongiform change'), PrP(sc) deposits, and the blood vessels were studied in immunolabelled sections of the cerebral cortex and cerebellum in eleven cases of the common M/M1 subtype of sCJD. Both the vacuolation and the PrP(sc) deposits were spatially correlated with the blood vessels; the PrP(sc) deposits being more focally distributed around the vessels than the vacuoles. The frequency of positive spatial correlations was similar in the different gyri of the cerebral cortex, in the upper and lower cortical laminae, and in the molecular layer of the cerebellum. It is hypothesized that the spatial correlation is attributable to factors associated with the blood vessels which promote the aggregation of PrP(sc) to form deposits rather than representing the hematogenous spread of the disease. The aggregated form of PrP(sc) then enhances cell death and may encourages the development of vacuolation in the vicinity of the blood vessels.

Less protease-resistant PrP in a patient with sporadic CJD treated with intraventricular pentosan polysulphate

Treatment with intraventricular pentosan polysulphate (PPS) might be beneficial in patients with Creutzfeldt-Jakob disease. We report a 68-year-old woman with sporadic Creutzfeldt-Jakob disease who received continuous intraventricular PPS infusion (1-120 microg/kg/day) for 17 months starting 10 months after the onset of clinical symptoms. Treatment with PPS was well tolerated but was associated with a minor, transient intraventricular hemorrhage and a non-progressive collection of subdural fluid. The patient's overall survival time was well above the mean time expected for the illness but still within the normal range. Post-mortem examination revealed that the level of abnormal protease-resistant prion protein in the brain was markedly decreased compared with levels in brains without PPS treatment. These findings suggest that intraventricular PPS infusion might modify the accumulation of abnormal prion proteins in the brains of patients with sporadic Creutzfeldt-Jakob disease.

Prion removal effect of a specific affinity ligand introduced into the manufacturing process of the pharmaceutical quality solvent/detergent (S/D)‐treated plasma OctaplasLG®

A new chromatographic step for the selective binding of abnormal prion protein (PrP(Sc)) was developed, and optimization for PrP(Sc) capture was achieved by binding to an affinity ligand attached to synthetic resin particles. This step was implemented into the manufacturing process of the solvent/detergent (S/D)-treated biopharmaceutical quality plasma Octaplas to further improve the safety margin in terms of risk for variant Creutzfeldt-Jakob disease (vCJD) transmission. Intermediates and Octaplas final container material, spiked with hamster brain-derived PrP(Sc)-containing fractions, were used for experiments to establish the feasibility of introducing this novel chromatography step. The binding capacity per millilitre of ligand gel was determined under the selected manufacturing conditions. In addition, the specificity of the ligand gel to bind PrP(Sc) from human sources was investigated. A validated Western blot test was used for the identification and quantification of PrP(Sc). A reduction factor of > or = 3.0 log(10) could be demonstrated by Western blotting, utilizing the relevant Octaplas matrix from manufacturing. In this particular cell-free plasma solution, the PrP(Sc) binding capacity of the selected gel was very high (> or = 6 log(10) ID(50)/ml, equivalent to roughly 10 log(10) ID(50)/column at manufacturing scale). The gel binds specifically PrP(Sc) from both animal (hamster and mouse) and human (sporadic and variant CJD) sources. This new single-use, disposable PrP(Sc)-harvesting gel ensures a very high capacity in terms of removing the pathogenic agent causing vCJD from the new generation OctaplasLG, in the event that prions can be found in plasma from donors incubating the disease and thereby contaminating the raw material plasma used for manufacturing.

Continuous intraventricular infusion of pentosan polysulfate: Clinical trial against prion diseases

Prion diseases are progressive neurological disorders due to abnormal prion protein (PrP(Sc)) deposition in the central nervous system. At present, there is no effective treatment available for any form of prion disease. Pentosan polysulfate (PPS) has been shown to prolong significantly the incubation period in mice with PrP(Sc) infection when administered to the cerebral ventricles in preclinical trials. In human studies conducted in European countries and Japan, intraventricular PPS was administered to patients with different forms of prion disease and was well tolerated. We report 11 patients with prion disease treated with intraventricular PPS at Fukuoka University from 2004. Cases included three familial CJD (two with V180I mutation, one GSS with P102L mutation), two iatrogenic CJD, and six sporadic CJD cases. At present, average survival period after treatment was 24.2 months (range, 4-49). Seven cases died of sepsis and pneumonia. Subdural effusion with various degrees was seen on CT scan in most cases. Except for these, adverse effects did not occur in the treatment period. Although our preliminary study of the new treatment with PPS by continuous intraventricular infusion showed no apparent improvement of clinical features in patients with prion disease, the possibility of extended survival in some patients receiving long-term PPS was suggested.

A traceback phenomenon can reveal the origin of prion infection

The transmission of prions to animals with incongruent prion protein (PrP) gene (referred to as cross-sequence transmission) results in a relatively long incubation period and can generate a new prion strain with unique transmissibility designated as a traceback phenomenon. For example, cross-sequence transmission of bovine spongiform encephalopathy (BSE) prions to human generated variant Creutzfeldt-Jakob disease (vCJD) prions which retained the transmissibility to mice expressing bovine PrP. This finding suggests that traceback studies could enable us to identify the origin of prions. There are two distinct phenotypes in dura mater graft-associated Creutzfeldt-Jakob disease (dCJD), with the majority represented by a non-plaque-type of dCJD (np-dCJD) and the minority by a plaque-type of dCJD (p-dCJD). To identify the origin of p-dCJD, we performed a traceback study using mice expressing human PrP with methionine homozygosity (129M/M) or valine homozygosity (129V/V) at polymorphic codon 129. The characteristics of p-dCJD such as the accumulation of abnormal isoform of PrP (PrP(Sc)) intermediate in size between type 1 and type 2, and plaque-type PrP deposition in the brain were maintained after transmission to the 129M/M mice. Furthermore, the 129V/V mice were more susceptible to p-dCJD prions than the 129M/M mice and produced type 2 PrP(Sc) that were identical in size to those from the 129V/V mice inoculated with sporadic CJD prions from a patient with 129V/V and type 2 PrP(Sc) (sCJD-VV2). In addition, we performed intracerebral transmission of sCJD-VV2 prions to the 129M/M mice as an experimental model for p-dCJD. These 129M/M mice showed the accumulation of the intermediate type PrP(Sc) and plaque-type PrP deposition in the brain. These results suggest that p-dCJD could be caused by cross-sequence transmission of sCJD-VV2 prions to individuals with the 129M/M genotype.

The kuru infectious agent is a unique geographic isolate distinct from Creutzfeldt–Jakob disease and scrapie agents

Human sporadic Creutzfeldt-Jakob disease (sCJD), endemic sheep scrapie, and epidemic bovine spongiform encephalopathy (BSE) are caused by a related group of infectious agents. The new U.K. BSE agent spread to many species, including humans, and clarifying the origin, specificity, virulence, and diversity of these agents is critical, particularly because infected humans do not develop disease for many years. As with viruses, transmissible spongiform encephalopathy (TSE) agents can adapt to new species and become more virulent yet maintain fundamentally unique and stable identities. To make agent differences manifest, one must keep the host genotype constant. Many TSE agents have revealed their independent identities in normal mice. We transmitted primate kuru, a TSE once epidemic in New Guinea, to mice expressing normal and approximately 8-fold higher levels of murine prion protein (PrP). High levels of murine PrP did not prevent infection but instead shortened incubation time, as would be expected for a viral receptor. Sporadic CJD and BSE agents and representative scrapie agents were clearly different from kuru in incubation time, brain neuropathology, and lymphoreticular involvement. Many TSE agents can infect monotypic cultured GT1 cells, and unlike sporadic CJD isolates, kuru rapidly and stably infected these cells. The geographic independence of the kuru agent provides additional reasons to explore causal environmental pathogens in these infectious neurodegenerative diseases.

Wernicke encephalopathy and Creutzfeldt-Jakob disease

We assessed the prevalence of Wernicke encephalopathy (WE) in all 657 cases suspected of Creutzfeldt-Jakob (CJD) referred from 2001 to 2006 to the French Neuropathology Network of CJD. Clinical, biological and imaging data were reviewed when the diagnosis of WE was made at autopsy. No CJD was found in five cases suspected of sporadic CJD. In these five cases, myoclonus had been observed in four, CSF 14-3-3 protein in two. In 14 other cases, WE was combined with CJD, 13 of which were sporadic. These belonged mainly to the molecular variants of sporadic CJD associated with a long duration of disease. This stresses the necessity of remaining alert to the diagnosis of WE when CJD is suspected.

Human platelets as a substrate source for the in vitro amplification of the abnormal prion protein (PrPSc) associated with variant Creutzfeldt‐Jakob disease

Four recent cases of transfusion-related transmission of variant Creutzfeldt-Jakob disease (vCJD) highlight the need to develop a highly sensitive and specific screening test to detect infectivity in the blood of asymptomatic infected individuals. Protein misfolding cyclic amplification (PMCA), a method for the amplification of minute amounts of disease-associated abnormal prion protein (PrP(Sc)) to readily detectable levels, could be incorporated into such a test provided that a suitable substrate source for routine use in human PMCA reactions can be found. With the use of seed sources from individuals with variant and sporadic CJD, the use of human platelets (PLTs) as a PMCA substrate source was evaluated. The effects of seed/substrate prion protein gene (PRNP) codon 129 genotype compatibility on amplification efficiency and freeze-thaw on a substrate's ability to support amplification and the degree of amplification achieved by serial PMCA (sPMCA) were investigated. Seed/substrate PRNP codon 129 compatibility was found to have a major influence on PrP(Sc) amplification efficiency. Individual substrates, of the same PRNP codon 129 genotype, could be pooled and stored frozen for use in subsequent PMCA reactions. A consistent 10-fold increase in PrP(Sc) detection sensitivity was achieved after each round of sPMCA, resulting in a 10,000-fold increase in detection sensitivity after four rounds, with no evidence of de novo PrP(Sc) production detected in the unseeded PLT substrate. Providing issues of seed/substrate PRNP codon 129 compatibility are taken into consideration human PLTs are a suitable, readily available, renewable substrate source for use in human PMCA applications.

MRI and clinical syndrome in dura materrelated Creutzfeldt-Jakob disease

Iatrogenic Creutzfeldt-Jakob disease (iCJD) is mainly associated with dura mater (DM) grafts and administration of human growth hormones (hGH). Data on disease course in DM-CJD are limited. We describe the clinical and diagnostic findings in this patient group with special emphasis on MRI signal alterations. Ten DM-CJD patients were studied for their clinical symptoms and diagnostic findings. The MRIs were evaluated for signal increase of the cortical and subcortical structures. DM-CJD patients had a median incubation time of 18 years and median disease duration of 7 months. The majority of patients were MM homozygous at codon 129 of the prion protein gene (PRNP) and presented with gait ataxia and psychiatric symptoms. No correlation between the graft site and the initial disease course was found. The MRI showed cortical and basal ganglia signal increase each in eight out of ten patients and thalamic hyperintensity in five out of ten cases. Of interest, patients with thalamic signal increase were homozygous for methionine. The MRI findings in DM-CJD largely resemble those seen in sporadic CJD, as the cortex and basal ganglia are mainly affected.

A quantitative study of the pathological changes in the cerebellum in 15 cases of variant Creutzfeldt-Jakob disease (vCJD).

To determine in the cerebellum in variant Creutzfeldt-Jakob disease (vCJD): (i) whether the pathology affected all laminae; (ii) the spatial topography of the pathology along the folia; (iii) spatial correlations between the pathological changes; and (iv) whether the pathology was similar to that of the common methionine/methionine Type 1 subtype of sporadic CJD. Sequential cerebellar sections of 15 cases of vCJD were stained with haematoxylin and eosin, or immunolabelled with monoclonal antibody 12F10 against prion protein (PrP) and studied using spatial pattern analysis. Loss of Purkinje cells was evident compared with control cases. Densities of the vacuolation and the protease-resistant form of prion protein (PrP(Sc)) (diffuse and florid plaques) were greater in the granule cell layer (GL) than the molecular layer (ML). In the ML, vacuoles and PrP(Sc) plaques occurred in clusters regularly distributed along the folia with larger clusters of vacuoles and diffuse plaques in the GL. There was a negative spatial correlation between the vacuoles and the surviving Purkinje cells in the ML. There was a positive spatial correlation between the vacuoles and diffuse PrP(Sc) plaques in the ML and GL. (i) all laminae were affected by the pathology, the GL more severely than the ML; (ii) the pathology was topographically distributed along the folia especially in the Purkinje cell layer and ML; (iii) pathological spread may occur in relation to the loop of anatomical connections involving the cerebellum, thalamus, cerebral cortex and pons; and (iv) there were pathological differences compared with methionine/methionine Type 1 sporadic CJD.

Genetic risk factors for variant Creutzfeldt–Jakob disease: a genome-wide association study

SummaryBackgroundHuman and animal prion diseases are under genetic control, but apart from PRNP (the gene that encodes the prion protein), we understand little about human susceptibility to bovine spongiform encephalopathy (BSE) prions, the causal agent of variant Creutzfeldt–Jakob disease (vCJD).MethodsWe did a genome-wide association study of the risk of vCJD and tested for replication of our findings in samples from many categories of human prion disease (929 samples) and control samples from the UK and Papua New Guinea (4254 samples), including controls in the UK who were genotyped by the Wellcome Trust Case Control Consortium. We also did follow-up analyses of the genetic control of the clinical phenotype of prion disease and analysed candidate gene expression in a mouse cellular model of prion infection.FindingsThe PRNP locus was strongly associated with risk across several markers and all categories of prion disease (best single SNP [single nucleotide polymorphism] association in vCJD p=2·5×10−17; best haplotypic association in vCJD p=1×10−24). Although the main contribution to disease risk was conferred by PRNP polymorphic codon 129, another nearby SNP conferred increased risk of vCJD. In addition to PRNP, one technically validated SNP association upstream of RARB (the gene that encodes retinoic acid receptor beta) had nominal genome-wide significance (p=1·9×10−7). A similar association was found in a small sample of patients with iatrogenic CJD (p=0·030) but not in patients with sporadic CJD (sCJD) or kuru. In cultured cells, retinoic acid regulates the expression of the prion protein. We found an association with acquired prion disease, including vCJD (p=5·6×10−5), kuru incubation time (p=0·017), and resistance to kuru (p=2·5×10−4), in a region upstream of STMN2 (the gene that encodes SCG10). The risk genotype was not associated with sCJD but conferred an earlier age of onset. Furthermore, expression of Stmn2 was reduced 30-fold post-infection in a mouse cellular model of prion disease.InterpretationThe polymorphic codon 129 of PRNP was the main genetic risk factor for vCJD; however, additional candidate loci have been identified, which justifies functional analyses of these biological pathways in prion disease.FundingThe UK Medical Research Council.

Introduction

Introduction

Association of a null allele of SPRN with variant Creutzfeldt–Jakob disease

Background:No susceptibility genes have been identified in human prion disase, apart from the prion protein gene (PRNP). The gene SPRN, encodes Shadoo (Sho, shadow of prion protein) which has protein...