Prion protein immunocytochemistry: reliable protocols for the investigation of Creutzfeldt-Jakob disease

Mechanisms of prion-induced neurodegeneration

Transmissible spongiform encephalopathies (TSEs), or prion diseases, are fatal neurodegenerative disorders characterised by long incubation period, short clinical duration, and transmissibility to susceptible species. Neuronal loss, spongiform changes, gliosis and the accumulation in the brain of the misfolded version of a membrane-bound cellular prion protein (PrP(C)), termed PrP(TSE), are diagnostic markers of these diseases. Compelling evidence links protein misfolding and its accumulation with neurodegenerative changes. Accordingly, several mechanisms of prion-mediated neurotoxicity have been proposed. In this paper, we provide an overview of the recent knowledge on the mechanisms of neuropathogenesis, the neurotoxic PrP species and the possible therapeutic approaches to treat these devastating disorders.

Fate of pathological prion (PrP(sc)92-138) in soil and water: prion-clay nanoparticle molecular dynamics

Pathogenic prion protein scrapie (PrP(sc)) may contaminate soils for decades and remain in water in colloidal suspension, providing infection pathways for animals through the inhalation of ingested dust and soil particles, and drinking water. We used molecular dynamics simulations to understand the strong binding mechanism of this pathogenic peptide with clay mineral surfaces and compared our results to experimental works. We restricted our model to the moiety PrP(92-138), which is a portion of the whole PrP(sc) molecule responsible for infectivity and modeled it using explicit solvating water molecules in contact with a pyrophyllite cleavage plane. Pyrophyllite is taken as a model for common soil clay, but it has no permanent structural charge. However, partial residual negative charges occur on the cleavage plane slab surface due to a slab charge unbalance. The charge is isotropic in 2D and it was balanced with K(+) ions. After partially removing potassium ions, the peptide anchors to the clay surface via up to 10 hydrogen bonds, between protonated lysine or histidine residues and the oxygen atoms of the siloxane cavities. Our results provide insight to the mechanism responsible for the strong association between the PrP(sc) peptide and clay nanoparticles and the associations present in contaminated soil and water which may lead to the infection of animals.

Formation of amyloid fibrils from β-amylase

Fibril formation has been considered a significant feature of amyloid proteins. However, it has been proposed that fibril formation is a common property of many proteins under appropriate conditions. We studied the fibril formation of β-amylase, a non-amyloid protein rich in α-helical structure, because the secondary structure of β-amylase is similar to that of prions. With the conditions for the fibril formation of prions, β-amylase proteins were converted into amyloid fibrils. The features of β-amylase proteins and fibrils are compared to prion proteins and fibrils. Furthermore, the cause of neurotoxicity in amyloid diseases is discussed.

Antigen retrieval using sodium hydroxide for prion immunohistochemistry in bovine spongiform encephalopathy and scrapie

Formalin-fixed and paraffin wax-embedded (FFPE) tissue sections are usually used for histopathological and immunohistochemical analyses in prion diseases in animals and man. However, formalin fixation cross-links proteins, reducing disease-associated prion protein (PrP(Sc)) immunolabelling. To detect PrP(Sc) in animals naturally affected with bovine spongiform encephalopathy (BSE) and scrapie, we applied minimal pretreatment with sodium hydroxide (NaOH). This simple pretreatment, combined with enzymatic digestion using proteinase K (PK), was equally effective in the detection of PrP(Sc) in FFPE tissue, and superior in terms of speed, compared with the usual autoclaving method. The most effective results, without any section loss, were obtained with 10 μg/ml PK in phosphate buffered saline containing 0.1% Triton-X at room temperature for 10 min and 150 mM NaOH at 60 °C for 10 min. By this simple procedure, PrP(Sc) was visualized in the brain of animals with BSE and scrapie using a range of anti-PrP primary antibodies.

Brain biopsy in dementia: clinical indications and diagnostic approach

Brain biopsy may be performed to make a definitive diagnosis in patients with rapidly progressive dementia. To assess the value of this procedure, we previously studied 90 consecutive cerebral biopsies performed in the tertiary referral centre of the National Hospital for Neurology and Neurosurgery, Queen Square between 1989 and 2003 (6 biopsies/year). Fifty-seven percent of all biopsies were diagnostic with Alzheimer's disease (18%), Creutzfeldt-Jakob disease (CJD) (12%) and inflammatory disorders (9%) being the most frequent. In the non-diagnostic group and for the series as a whole non-specific gliosis was the commonest diagnosis (37%). Treatment was altered because of information obtained from neuropathological findings in 11% of cases. To identify changes in practice that may have occurred due to recent advances in clinical assessment and improved histopathological techniques, we performed a follow-up study of 19 brain biopsies (approximately 3 cases/year) carried out for a dementing illness in the same centre between 2004 and 2009. These data suggest that brain biopsy may be less frequently used to help clinical diagnosis whilst its diagnostic yield increased from 57 to 74%. The commonest diagnosis was CJD, mostly suspected during life. Amongst the diagnoses, there were two cases of vasculitis and two cases of primary neurodegenerative dementia. These data suggest that improved clinical selection criteria supported by advances in diagnostic testing may result in brain biopsy being less frequently required, although it may still provide useful diagnostic information in difficult cases. We propose algorithms to aid the clinician in selecting appropriate patients for a biopsy and the neuropathologist in assessing a biopsy specimen.

Human prion diseases: from antibody screening to a standardized fast immunodiagnosis using automation

Demonstration of pathological prion protein accumulation in the central nervous system is required to establish the diagnosis of transmissible subacute encephalopathies. In humans, this is frequently achieved using prion protein immunohistochemistry in paraffin-embedded tissue, a technique that requires multiple epitope retrieval and denaturing pretreatments. In addition to being time-consuming, this procedure induces tissue alterations that preclude accurate morphological examination. The aim of this study was to simplify prion protein immunohistochemistry procedure in human tissue, together with increased sensitivity and specificity. We screened a panel of 50 monoclonal antibodies produced using various immunogens (human and ovine recombinant prion protein, prion protein peptides, denatured scrapie-associated fibrils from 263K-infected Syrian hamsters) and directed against different epitopes along the human prion protein sequence. A panel of different forms of genetic, infectious and sporadic transmissible subacute encephalopathies was assessed. The monoclonal 12F10 antibody provided a high specificity and fast immunodiagnosis with very limited denaturing pretreatments. A standardized and reliable fast immunostaining procedure was established using an automated diagnostic system (Nexes, Ventana Medical Systems) and allowed prion protein detection in the central nervous system and in tonsil biopsies. It was evaluated in a series of 300 patients with a suspected diagnosis of transmissible subacute encephalopathies and showed high sensitivity and specificity.

Contact-induced structure transformation in transmembrane prion propagation

Based on recent experimental evidences of the transmission of prion diseases due to a particular transmembrane form (termed (Ctm)PrP), we propose a theoretical model for the molecular mechanism of such conformational diseases, in which a misfolded (Ctm)PrP induces a similar misfolding of another (Ctm)PrP. Computer simulations are performed to investigate the correlation between folding time and the concentration of misfolded PrP in various processes, including dimerization, trimerization, and cooperative dimerization. By comparing with the experimental correlation curve between incubation time and injected dose of scrapie prions, we conclude that cooperative dimerization may play an important role in the pathological mechanism of prion diseases.

Comparative neuropathology of Kuru with the new variant of Creutzfeldt-Jakob disease: evidence for strain of agent predominating over genotype of host

The three major influences on the phenotype of the transmissible spongiform encephalopathies are believed to be strain of agent, route of infection and host genotype. We have compared the pathologic profiles and genotypes of the new variant of Creutzfeldt-Jakob disease (vCJD) and kuru. The comparison reveals that there are distinct lesional differences particularly in the prion protein (PrP) load and distribution as seen by immunohistochemistry. The clinico-pathologic phenotypes and the genotypes of these two diseases are sufficiently different to suggest that the strain of agent may play a greater role than any presumptive common route of peripherally acquired infection.

Effective antigen-retrieval method for immunohistochemical detection of abnormal isoform of prion proteins in animals

For immunohistochemistry of the prion diseases, several pretreatment methods to enhance the immunoreactivity of human and animal abnormal proteinase-resistant prion protein (PrP(Sc)) on the tissue sections have been employed. The method of 121 degree C hydrated autoclaving pretreatment or the combination method of 121 degree C hydrated autoclaving with a certain chemical reagent (formic acid or proteinase K, etc) are now widely used. We found that an improved hydrated autoclaving method at 135 degrees C, more effectively enhanced PrP(Sc) immunoreactivity for the antibodies recognizing the linear epitope. In addition, this method was more effective for the long-term fixation samples as compared with other previous methods. However, this modified method could not retrieve PrP(Sc) antigenic epitopes composed of conformational structures or several discontinuous epitopes. We describe the comparative studies between our improved method and other antigen-retrieval procedures reported previously. Based on the differences of reaction among the antibodies, we also discuss the mechanisms of the hydrated autoclaving methods to retrieve PrP(Sc) immunoreactivity.

Scrapie-infected GT1-1 cells show impaired function of voltage-gated N-type calcium channels (Cav 2.2) which is ameliorated by quinacrine treatment

Prions are transmissible pathogens that cause neurodegenerative diseases, although the mechanisms behind the nervous system dysfunctions are unclear. To study the effects of a prion infection on voltage-gated calcium channels, scrapie-infected gonadotropin-releasing hormone neuronal cells (ScGT1-1) in culture were depolarized by KCl and calcium responses recorded. Lower calcium responses were observed in infected compared to uninfected cells. This effect was still observed when L-type calcium channels were blocked by nimodipine. After inhibition of N-type calcium channels with omega-conotoxin GVIA, there was no difference in calcium responses. The calcium responses after nimodipine treatment became progressively lower during infection, but there was no major loss of the cellular prion protein (PrP(C)) or marked increase in accumulation of the abnormal prion protein (PrP(Sc)) in the cultures. These results indicate that scrapie infection causes a dysfunction of voltage-gated N-type calcium channels, which is exacerbated slowly over time. Quinacrine treatment cleared PrP(Sc) and restored calcium responses in the ScGT1-1 cultures.

Scrapie and chronic wasting disease

Scrapie and CWD share many features. There are marked similarities in the clinical presentations, the lesions, and the pathogenesis of these diseases, and some similarities in the epidemiology. Extrapolation from the scrapie model of TSE disease to CWD--which occurs in three different species, and should not be considered to be uniform in their response--may be erroneous, however. Such differences may influence diagnostics (e.g., the amount and distribution of PrPC in these different species), pathogenesis (e.g., the influence of genetics on susceptibility and resistance), and epidemiology (e.g., the mode and dynamics of transmission and influences of domestication). IHC is used widely for diagnostics and in the study of the pathogenesis of scrapie and CWD. This technique holds promise for antemortem diagnosis of infection in the peripheral lymphoid tissues such as lymphoid follicles of the nictitating membrane and the tonsil.

Phenotyping of protein-prion (PrPsc)-accumulating cells in lymphoid and neural tissues of naturally scrapie-affected sheep by double-labeling immunohistochemistry

Transmissible spongiform encephalopathies are fatal neurodegenerative diseases characterized by amyloid deposition of protein-prion (PrPsc), the pathogenic isoform of the host cellular protein PrPc, in the immune and central nervous systems. In the absence of definitive data on the nature of the infectious agent, PrPsc immunohistochemistry (IHC) constitutes one of the main methodologies for pathogenesis studies of these diseases. In situ PrPsc immunolabeling requires formalin fixation and paraffin embedding of tissues, followed by post-embedding antigen retrieval steps such as formic acid and hydrated autoclaving treatments. These procedures result in poor cellular antigen preservation, precluding the phenotyping of cells involved in scrapie pathogenesis. Until now, PrPsc-positive cell phenotyping relied mainly on morphological criteria. To identify these cells under the PrPsc IHC conditions, a new, rapid, and highly sensitive PrPsc double-labeling technique was developed, using a panel of screened antibodies that allow specific labeling of most of the cell subsets and structures using paraffin-embedded lymphoid and neural tissues from sheep, leading to an accurate identification of ovine PrPsc-accumulating cells. This technique constitutes a useful tool for IHC investigation of scrapie pathogenesis and may be applicable to the study of other ovine infectious diseases.

Prion diseases: what is the neurotoxic molecule?

A great deal of effort has been devoted during the past 20 years to defining the chemical nature of prions, the infectious agents responsible for transmissible spongiform encephalopathies. In contrast, much less attention has been paid to elucidating how prions actually damage the central nervous system. Although it is commonly assumed that PrP(Sc), the protein constituent of infectious prions, is the primary culprit, increasing evidence indicates that this may not be the case. Several alternative molecular forms of PrP are reasonable candidates for the neurotoxic species in prion diseases, although it is still too early to tell whether these or other ones will turn out to be the true instigating factors. The cellular pathways activated by neurotoxic forms of PrP that ultimately result in neuronal death are also being investigated, and several possible mechanisms have been uncovered, including the operation of quality control processes in the endoplasmic reticulum. Elucidating the distinction between the infectious and neurotoxic forms of PrP has important implications for designing therapy of prion diseases, as well as for understanding pathogenic mechanisms operative in other neurodegenerative disorders and the role of prion-like states in biology.

PrP immunohistochemistry: different protocols, including a procedure for long formalin fixation, and a proposed schematic classification for deposits in sporadic Creutzfeldt-Jakob disease

The use of immunohistochemistry on formalin-fixed and paraffin-embedded tissue has greatly improved the neuropathological diagnosis of Creutzfeldt-Jakob disease and the other subacute spongiform encephalopathies in human and animals. Two pitfalls of this technique, however, currently exist: low sensitivity after long formalin fixation and difficulties in interpreting some images. Here we review the protocols currently in use for the pretreatment of sections allowing PrP detection by immunohistochemistry. In addition, a technique useful after long formalin fixation is reported: enzymatic digestion with proteinase K (24 degrees C, 1/100 for 8 minutes) was employed in addition to the usual autoclaving (121 degrees C for 10 minutes) followed by formic acid (99% for 5 minutes) and 4M guanidine thiocyanate (4 degrees C for 2 hours). This allowed a substantial increase in the sensitivity of 3F4 immunohistochemistry on paraffin-embedded tissue, especially after prolonged formalin fixation. In addition, we suggest a simple method for classification of PrP immunolabelling in sporadic Creutzfeldt-Jakob disease that would allow easy comparisons.

A three-sister sibship of Gerstmann-Sträussler-Scheinker disease with a CJD phenotype

OBJECTIVE

To describe a rare phenotypic variant of P102L Gerstmann-Sträussler-Scheinker disease (GSS).

BACKGROUND

Classic GSS is characterized by an early age at onset, prominent cerebellar signs with a slowly evolving dementia, and a neuropathology including multifocal PrP-positive plaques and variable but usually modest spongiform change.

METHODS

Clinical, neuropathologic, immunohistochemical, and molecular genetic analysis of three sisters in a Hungarian family was performed.

RESULTS

The clinical course of all three sisters was indistinguishable from sporadic Creutzfeldt-Jakob disease (CJD). Neuropathologic examination revealed spongiform changes, PrP (prion)-positive unicentric "kuru" or multicentric plaques, and abundant beta-A4-positive senile plaques. Molecular genetic analysis of the PRNP gene showed the heterozygous codon P102L mutation of classic GSS, with the methionine encoding allele of a heterozygous codon 129 coupled to the mutant 102 allele.

CONCLUSION

The authors report the second recorded example of a sporadic CJD phenotype occurring in association with the P102L GSS genotype, and the first instance in which the phenotype was the rule rather than the exception, or was associated with prominent beta-A4 plaque formation.

Prion protein immunoreactivity in brain samples from an unselected autopsy population: findings in 200 consecutive cases

Immunostaining for prion protein (PrP) using the KG9 monoclonal antibody was undertaken on brain sections from an unselected group of 200 post-mortem cases. One case of clinically diagnosed vCJD was confirmed and showed widespread abundant PrP immunostaining with KG9 and somewhat less abundant PrP with another monoclonal antibody, 3F4. PrP immunostaining seen with KG9 was insensitive to proteinase K pretreatment in sections from this case of vCJD. Among the remaining 199 cases, sections from 84 (42%) showed small amounts of PrP immunoreactivity with the KG9 antibody, mainly localized to neurones, neural processes and argyrophilic plaques of the type seen in ageing and Alzheimer's disease. Purkinje cells, swollen (ischaemic) axons, macrophages and microglials cells were also occasionally labelled with this antibody in non-CJD cases. Pre-treatment of adjacent sections from non-CJD cases with positive KG9 staining abolished this staining, indicating that it represented the cellular form of PrP. There were differences in age, sex and cause of death in non-CJD cases with some PrP immunostaining patterns compared with cases lacking any staining. Specifically, a younger mean age, more females and fewer cardiac deaths were found among those with neuronal PrP staining patterns. Staining of some features was also significantly associated. These findings need to be taken into account when PrP immunostaining is used to diagnose prion diseases. They may indicate that cellular PrP is increased in the human brain under some circumstances and provide insight into the handling of this protein by human brain cells.

Antigen retrieval in prion protein immunohistochemistry

Transmissible spongiform encephalopathies are a group of neurodegenerative diseases occurring in both humans and animals and are most likely caused by prions. Neuropathological confirmation of the clinical diagnosis has been a problem because of the difficulty in epitope retrieval from formalin-fixed, paraffin-embedded brain specimens. Many different protocols for the detection of prions in brain tissue have been used. Thus far, picric and/or formic acid, steam autoclaving at 121C of sections, microwave treatment, and 4 M guanidine thiocyanate treatment have been suggested. The objective of our experiment was to obtain the standard pretreatment(s) resulting in optimal immunostaining. In the experiment, successive tissue slides of brain specimens of several Creutzfeldt-Jakob disease and control patients were stained using different combinations of pretreatments. Using densitometric analysis, several well-defined locations per section were examined and prion immunostaining was quantified. The results showed that autoclaving is necessary for antigen retrieval and cannot be substituted by microwave treatment. The best results were obtained when the following combination was used in the specified order: 15 min saturated picric acid, 10 min steam autoclaving at 121C, 5 min 88% formic acid, and 2 hr 4 M guanidine thiocyanate at 4C. (J Histochem Cytochem 47:1465-1470, 1999)

Early destruction of the extracellular matrix around parvalbumin-immunoreactive interneurons in Creutzfeldt-Jakob disease

GABA-interneurons immunoreactive (IR) for the calcium-binding protein parvalbumin are lost during the early stages of Creutzfeldt-Jakob disease (CJD) and diminution in their number may partially account for the neurological disturbances manifested in patients suffering from this condition. The disease is characterized by a transformation of the prion protein, PrP(c)-a host-coded sialoglycoprotein-to its protease-resistant and putatively pathological form, PrP(CJD). And since this conversion is likely to take place at the cell surface, we were curious to know whether the "perineuronal net"-a characteristic accumulation of extracellular matrix in intimate contact with the surface of parvalbumin-IR neurons-is implicated in the early disappearance of the mantled cells. Using various lectins and antibodies as markers for the perineuronal net in brains of 21 CJD victims, we observed that this meshwork of extracellular matrix molecules is lost before the embraced parvalbumin-IR neurons themselves disappear. Hence, an interaction of PrP(c) and/or PrP(CJD) with components of the extracellular matrix around this subpopulation of nerve cells precipitates a sequence of as yet unknown events which culminates in the replacement of perineuronal nets by deposits of insoluble PrP(CJD). This change in the environment of the GABA-interneurons IR for parvalbumin may ultimately provoke their death.

Neuropathology of prion diseases

Prion diseases include sporadic forms such as Creutzfeldt-Jakob disease (CJD), familial forms (familial CJD), fatal familial insomnia, Gerstmann-Sträussler-Scheinker disease, and acquired forms (i.e., kuru, iatrogenic CJD). The most frequent of the latter include acquired forms secondary to injections of human cadaveric pituitary-derived growth hormone and the new variant of CJD--probably related to bovine spongiform encephalopathy. The communal lesions are neuronal loss, spongiosis and gliosis and, inconstantly, the presence of amyloid plaques and different kinds of small deposits immunolabeled with anti-prion (PrP) antibodies. Their number and topography are variable. Recent works have shown the role of the host genotype, especially of codon 129, in the susceptibility to these diseases. We have tried to correlate neuropathology with the genotype of codon 129 and the type of PrP to establish a molecular classification.

A transmembrane form of the prion protein in neurodegenerative disease

At the endoplasmic reticulum membrane, the prion protein (PrP) can be synthesized in several topological forms. The role of these different forms was explored with transgenic mice expressing PrP mutations that alter the relative ratios of the topological forms. Expression of a particular transmembrane form (termed CtmPrP) produced neurodegenerative changes in mice similar to those of some genetic prion diseases. Brains from these mice contained CtmPrP but not PrPSc, the PrP isoform responsible for transmission of prion diseases. Furthermore, in one heritable prion disease of humans, brain tissue contained CtmPrP but not PrPSc. Thus, aberrant regulation of protein biogenesis and topology at the endoplasmic reticulum can result in neurodegeneration.

Prion protein genotype and pathological phenotype studies in sporadic Creutzfeldt-Jakob disease

A comparative semi-automated morphometric study was performed on the distribution of prion protein, spongiform change and astrocytosis in the brains of nine cases of sporadic Creutzfeldt-Jakob disease of differing genotype at the methionine-valine polymorphism at codon 129 of the prion protein gene. Custom-designed image analysis software was used to produce objective figures for each of the different pathological features throughout 13 different areas of the brain used for analysis. A significant positive correlation was observed between prion protein deposition and astrocytosis in all cases and no significant correlation was observed between spongiform change and prion protein deposition. Different patterns of pathology were found to relate to codon 129 genotype; valine homozygosity favoured the targeting of pathology to deep grey matter structures, while methionine homozygosity favoured cortical targeting of pathology. These results provide evidence that prion protein deposition is closely associated with an astrocytic reaction and suggest that codon 129 genotype may influence the pathological phenotype.

Normal host prion protein necessary for scrapie-induced neurotoxicity

Accumulation of the prion protein PrPSc, a pathological and protease-resistant isoform of the normal host protein PrPC, is a feature of prion disease such as scrapie. It is still unknown whether scrapie pathology comes about by neurotoxicity of PrPSc, acute depletion of PrPC, or some other mechanism. Here we investigate this question by grafting neural tissue overexpressing PrPC into the brain of PrP-deficient mice which are scrapie-resistant and do not propagate infectivity. After intracerebral inoculation with scrapie prions, the grafts accumulated high levels of PrPSc and infectivity and developed the severe histopathological changes characteristic of scrapie. Moreover, substantial amounts of graft-derived PrPSc migrated into the host brain. Even 16 months after inoculation no pathological changes were seen in PrP-deficient tissue, not even in the immediate vicinity of the grafts. Therefore, in addition to being resistant to scrapie infection, brain tissue devoid of PrPC is not damaged by exogenous PrPSc.

Human prion diseases

The classical prion diseases in man comprise Creutzfeldt-Jakob disease (CJD), Kuru and Gerstmann-Sträussler-Scheinker syndrome (GSS). Recent advances in the biochemistry and the molecular biology of the transmissible agents responsible for these human spongiform encephalopathies have prompted renewed interest in their clinical and pathological features. A broadening spectrum of human prion diseases has now been identified including novel entities such as Fatal Familial Insomnia and variants of CJD and GSS characterised by specific abnormalities in the human prion protein (PrP) gene on chromosome 20. Accumulation of PrP in the central nervous system is a characteristic feature of all these disorders, although the relationship between PrP localisation, classical neuropathology, clinical features and genotype still requires clarification. A national surveillance project for CJD was established in 1990 in the United Kingdom in order to assess the possible implications of bovine spongiform encephalopathy for human health. The identification of an apparently new variant of CJD in young patients in UK raises the possibility of such a link; further studies are required to assess the significance of this observation.

Reactive microglia in Creutzfeldt-Jakob disease

Creutzfeldt-Jakob disease (CJD) is characterized by a loss of neurons accompanied by astrogliosis and spongiform changes in the neuropil. It has been recognized that reactive microglia occur in CJD but little is known about the regional distribution and extent of the microglial activation. We have, therefore, examined six brains from cases of sporadic CJD by immunohistochemical labelling of grey and white matter microglia from frontal, parietal, temporal, and occipital lobes, striatum, thalamus, cerebellum and brain stem with RCA-1, LCA, CD68, HLA-DR, and HAM56. Microglial activation occurred in the grey matter where astrogliosis and prion protein (PrP) deposits were prominent. Processes of activated microglia surrounded the outer rim of spongy vacuoles. A diffuse microglial response was seen in the white matter that was immunophenotypically different from grey matter. Double-labelling with microglial markers and anti-PrP showed that activated microglia did not contain PrP-immunoreactivity. Therefore a primary role of microglia in PrP processing seems unlikely. Activated microglia may contribute to neuronal damage in CJD due to their cytotoxic potential.

Creutzfeldt-Jakob disease after liver transplantation

We report a 57-year-old woman who died from Creutzfeldt-Jakob disease 2 years after a liver transplantation. The liver donor had no history of neurological disease. In one albumin donor, possible Creutzfeldt-Jakob disease developed 3 years later. The patient initially had cerebellar symptoms. Neuropathology included "Kuru-type" plaques and prion protein (PrP) deposits involving the cerebellum predominantly. The patient was homozygote valine at codon 129 of the PrP gene while the liver was homozygote methionine. This observation raises the possibility of transmission of Creutzfeldt-Jakob disease by the graft itself or the associated albumin transfusions and, on a wider extent, by nonneural tissue.

Pathology of the transmissible spongiform encephalopathies with special emphasis on ultrastructure

The transmissible spongiform encephalopathies are a group of genetic and infectious disorders which are exemplified by scrapie in animals and Creutzfeldt-Jakob disease in humans. The spongiform encephalopathies are characterized by symmetrical vacuolation of neurons and neuropil. Amyloid plaque formation similar to that found in Alzheimer's disease is conspicuous in many, but not all, of these diseases. The sub-cellular pathology features of the spongiform encephalopathies have been studied by conventional transmission electron microscopy, scanning electron microscopy, freeze fracture, negative staining and most recently by application of immunogold labelling methods. Although these studies have revealed many unusual structures, convincing virus-like particles have not been demonstrated. Considerable data, including important transgenic mouse studies, now suggest that a single cellular protein, designated prion protein, is necessary for infection. Ultrastructural immunogold studies have shown that prion protein is released from the surface of neurons and neurites, diffuses through the extracellular space around infected cells where it accumulates and finally becomes aggregated as amyloid fibrils. It is likely that the accumulation of prion protein within the extracellular space is instrumental in causing nerve cell dysfunction and, ultimately, neurological disease.

Creutzfeldt-Jakob disease and cerebral amyloid angiopathy

An 83-year-old female with no personal or familial neurological history developed progressive gait and speech disturbance and left motor deficit. She suffered intractable seizures and died 3 months after the onset of neurological signs. Neuropathology showed severe spongiosis and gliosis in the cortex and basal ganglia, and diffuse cerebral amyloid angiopathy. Immunostaining for prion protein (PrP) showed intense PrP positivity in areas of confluent spongiosis and some granular staining in astrocytes. The cortical vessel walls stained positively for beta/A4 amyloid but not for PrP amyloid. Both types of amyloid were only observed in pericapillary parenchyma, in areas with severe spongiosis. There were only a few tangles and neuritic plaques in the temporal cortex; amyloid plaques were not present either by silver stains or immunostains. There was neither arteriopathic leukoencephalopathy nor cerebral hemorrhage. Immunoblot analysis of brain extracts revealed an abnormal proteinase K-resistant isoform of PrP. Association of Creutzfeldt-Jakob disease and Cerebral amyloid angiopathy in the absence of Alzheimer changes in unusual. The association of PrP and beta/A4 amyloid deposits could have been fortuitous in an 83-year-old patient. An etiopathogenic relationship between beta/A4 amyloid deposition and PrP accumulation may also be considered.