Unexpected decrease of full-length prion protein in macaques inoculated with prion-contaminated blood products.

The presence of prion infectivity in the blood of patients affected by variant Creutzfeldt-Jakob disease (v-CJD), the human prion disease linked to the bovine spongiform encephalopathy (BSE), poses the risk of inter-human transmission of this fatal prion disease through transfusion. In the frame of various experiments, we have previously described that several cynomolgus macaques experimentally exposed to prion-contaminated blood products developed c-BSE/v-CJD, but the vast majority of them developed an unexpected, fatal disease phenotype focused on spinal cord involvement, which does not fulfill the classical diagnostic criteria of v-CJD. Here, we show that extensive analyses with current conventional techniques failed to detect any accumulation of abnormal prion protein (PrPv-CJD) in the CNS of these myelopathic animals, i.e., the biomarker considered responsible for neuronal death and subsequent clinical signs in prion diseases. Conversely, in the spinal cord of these myelopathic primates, we observed an alteration of their physiological cellular PrP pattern: PrP was not detectable under its full-length classical expression but mainly under its physiological terminal-truncated C1 fragment. This observed disappearance of the N-terminal fragment of cellular PrP at the level of the lesions may provide the first experimental evidence of a link between loss of function of the cellular prion protein and disease onset. This original prion-induced myelopathic syndrome suggests an unexpected wide extension in the field of prion diseases that is so far limited to pathologies associated with abnormal changes of the cellular PrP to highly structured conformations.

Non-human primates in prion diseases.

The fascinating history of prion diseases is intimately linked to the use of nonhuman primates as experimental models, which brought so fundamental and founding information about transmissibility, pathogenesis, and resistance of prions. These models are still of crucial need for risk assessment of human health and may contribute to pave a new way towards the moving field of prion-like entities which now includes the main human neurodegenerative diseases (especially Alzheimer's and Parkinson's diseases).

Phenotypic diversity of genetic Creutzfeldt-Jakob disease: a histo-molecular-based classification.

The current classification of sporadic Creutzfeldt-Jakob disease (sCJD) includes six major clinicopathological subtypes defined by the physicochemical properties of the protease-resistant core of the pathologic prion protein (PrPSc), defining two major PrPSc types (i.e., 1 and 2), and the methionine (M)/valine (V) polymorphic codon 129 of the prion protein gene (PRNP). How these sCJD subtypes relate to the well-documented phenotypic heterogeneity of genetic CJD (gCJD) is not fully understood. We analyzed molecular and phenotypic features in 208 individuals affected by gCJD, carrying 17 different mutations, and compared them with those of a large series of sCJD cases. We identified six major groups of gCJD based on the combination PrPSc type and codon 129 genotype on PRNP mutated allele, each showing distinctive histopathological characteristics, irrespectively of the PRNP associated mutation. Five gCJD groups, named M1, M2C, M2T, V1, and V2, largely reproduced those previously described in sCJD subtypes. The sixth group shared phenotypic traits with the V2 group and was only detected in patients carrying the E200K-129M haplotype in association with a PrPSc type of intermediate size ("i") between type 1 and type 2. Additional mutation-specific effects involved the pattern of PrP deposition (e.g., a "thickened" synaptic pattern in E200K carriers, cerebellar "stripe-like linear granular deposits" in those with insertion mutations, and intraneuronal globular dots in E200K-V2 or -M"i"). A few isolated cases linked to rare PRNP haplotypes (e.g., T183A-129M), showed atypical phenotypic features, which prevented their classification into the six major groups. The phenotypic variability of gCJD is mostly consistent with that previously found in sCJD. As in sCJD, the codon 129 genotype and physicochemical properties of PrPSc significantly correlated with the phenotypic variability of gCJD. The most common mutations linked to CJD appear to have a variable and overall less significant effect on the disease phenotype, but they significantly influence disease susceptibility often in a strain-specific manner. The criteria currently used for sCJD subtypes can be expanded and adapted to gCJD to provide an updated classification of the disease with a molecular basis.

History of Pick's disease.

After a short summary of Arnold Pick's biography, the history of how Pick's disease (PiD) was reported is presented, from its clinical symptoms to its molecular characterization. The macroscopic description of frontotemporal atrophy by Pick is recounted followed by a description of the histological lesions observed by Alzheimer and the progressive characterization of the disease. The subsequent diagnosis has since relied on ultrastructural findings as well as immunohistochemical and biochemical techniques. The discovery of the role of the microtubule-associated τ-protein, encoded by chromosome 17, more specifically of the 3R isoform, has led to the inclusion of PiD in the 3R tauopathies. Today, both sporadic and familial PiDs, including the more frequent behavioral form, are considered as frontotemporal dementias. Experimental models have reproduced some of the lesions but the prion-like hypothesis concerning PiD has not, as yet, been proven.

Dejerine-Roussy syndrome: Historical cases.

On June 7, 1906, Jules Dejerine (1849-1917) and Gustave Roussy (1874-1948) presented to the Société de Neurologie de Paris the first description of the thalamic syndrome with serial-section microscopic images. They also provided the first account of central poststroke pain (CPSP). They suggested that pain is one of the primary symptoms of the syndrome, although one of their own patients ("Hud") did not have pain. Several contemporary studies have highlighted the involvement of the anterior part of the pulvinar (PuA) in patients with CPSP of thalamic origin. Two historical observations (cases Jos and Hud) are reviewed here using the Morel nuclei staining atlas (2007). Dejerine and Roussy proposed the "irritative theory" to explain CPSP of thalamic origin and, in line with the most recent literature, they invoked the involvement of the PuA. When matching images for the Jos and Hud cases with the Morel atlas, it appears that the lesions involved what Dejerine then termed the noyau externe; that is, the ventral posterolateral nucleus and the PuA. In the Jos case, the lesion extended medially to what Dejerine termed the noyau médian de Luys; that is, the central medial-parafascicular nuclei, whereas in the Hud case the lesion extended more inferiorly. From the finding in the Hud case, one can hypothesize that impairment of the PuA alone does not assure pain. The work of Dejerine and Roussy, based on clinico-anatomical correlations, remains relevant to this day.

Small-molecule induction of Aß-42 peptide production in human cerebral organoids to model Alzheimer's disease associated phenotypes.

Human mini-brains (MB) are cerebral organoids that recapitulate in part the complexity of the human brain in a unique three-dimensional in vitro model, yielding discrete brain regions reminiscent of the cerebral cortex. Specific proteins linked to neurodegenerative disorders are physiologically expressed in MBs, such as APP-derived amyloids (Aß), whose physiological and pathological roles and interactions with other proteins are not well established in humans. Here, we demonstrate that neuroectodermal organoids can be used to study the Aß accumulation implicated in Alzheimer's disease (AD). To enhance the process of protein secretion and accumulation, we adopted a chemical strategy of induction to modulate post-translational pathways of APP using an Amyloid-ß Forty-Two Inducer named Aftin-5. Secreted, soluble Aß fragment concentrations were analyzed in MB-conditioned media. An increase in the Aß42 fragment secretion was observed as was an increased Aß42/Aß40 ratio after drug treatment, which is consistent with the pathological-like phenotypes described in vivo in transgenic animal models and in vitro in induced pluripotent stem cell-derived neural cultures obtained from AD patients. Notably in this context we observe time-dependent Aß accumulation, which differs from protein accumulation occurring after treatment. We show that mini-brains obtained from a non-AD control cell line are responsive to chemical compound induction, producing a shift of physiological Aß concentrations, suggesting that this model can be used to identify environmental agents that may initiate the cascade of events ultimately leading to sporadic AD. Increases in both Aß oligomers and their target, the cellular prion protein (PrPC), support the possibility of using MBs to further understand the pathophysiological role that underlies their interaction in a human model. Finally, the potential application of MBs for modeling age-associated phenotypes and the study of neurological disorders is confirmed.

Unexpected prion phenotypes in experimentally transfused animals: predictive models for humans?

The recently reevaluated high prevalence of healthy carriers (1/2,000 in UK) of variant Creutzfeldt-Jakob Disease (v-CJD), whose blood might be infectious, suggests that the evolution of this prion disease might not be under full control as expected. After experimental transfusion of macaques and conventional mice with blood derived from v-CJD exposed (human and animal) individuals, we confirmed in these both models the transmissibility of v-CJD, but we also observed unexpected neurological syndromes transmissible by transfusion: despite their prion etiology confirmed through transmission experiments, these original cases would escape classical prion diagnosis, notably in the absence of detectable abnormal PrP with current techniques. It is noteworthy that macaques developed an original, yet undescribed myelopathic syndrome associating demyelination and pseudo-necrotic lesions of spinal cord, brainstem and optical tract without affecting encephalon, which is rather evocative of spinal cord disease than prion disease in human medicine. These observations strongly suggest that the spectrum of human prion diseases may extend the current field restricted to the phenotypes associated to protease-resistant PrP, and may notably include spinal cord diseases.

Experimental transfusion of variant CJD-infected blood reveals previously uncharacterised prion disorder in mice and macaque.

Exposure of human populations to bovine spongiform encephalopathy through contaminated food has resulted in <250 cases of variant Creutzfeldt-Jakob disease (vCJD). However, more than 99% of vCJD infections could have remained silent suggesting a long-term risk of secondary transmission particularly through blood. Here, we present experimental evidence that transfusion in mice and non-human primates of blood products from symptomatic and non-symptomatic infected donors induces not only vCJD, but also a different class of neurological impairments. These impairments can all be retransmitted to mice with a pathognomonic accumulation of abnormal prion protein, thus expanding the spectrum of known prion diseases. Our findings suggest that the intravenous route promotes propagation of masked prion variants according to different mechanisms involved in peripheral replication.

Long-term AIDS-related PCNSL outcomes with HD-MTX and combined antiretroviral therapy.

OBJECTIVE: To assess the characteristics and outcomes of patients with AIDS-related primary CNS lymphoma (AR-PCNSL) in the combined antiretroviral therapy (cART) era systematically treated with high-dose methotrexate (HD-MTX). METHODS: We retrospectively analyzed (intention-to-treat analysis) 51 consecutive patients with AR-PCNSL (median age 39 years) who were diagnosed from 1996 to 2014 and treated with a median of 6 (range 1-15) infusions of HD-MTX (3 g/m2) combined with cART. RESULTS: Median all-patients' and survivors' follow-up lasted 23 (range 0-186) and 76 (range 23-186) months, respectively. At PCNSL diagnosis, 83% of the patients were on cART, median plasma HIV load was 175,600 copies/mL, and median CD4+ T-cell count was 24/µL. Median Eastern Cooperative Oncology Group performance status was 2 (range 1-4). Median overall survival (OS) was 5.7 years, with 5- and 10-year rates of 48% and 41%. Median time to progression was not reached (69% at 10 months). PCNSL was the direct cause of 14 deaths, all observed within the 10 months after its diagnosis: 6 patients died before HD-MTX could be administered, 4 had refractory disease, and 4 relapsed. Multivariate analyses retained time interval between AIDS diagnosis and PCNSL diagnosis, age at AR-PCNSL diagnosis, and deep brain structure involvement as independent OS-predictive factors. To restore effective immune function, cART tailored to HIV genotypes was started and combined with HD-MTX; no interactions and no immune reconstitution inflammatory syndrome occurred. No patient died of acute treatment-related toxicity, and 21 of 51 (41%) patients experienced grade 3/4 toxicity. CONCLUSIONS: Combined short-term HD-MTX monochemotherapy and optimal cART simply and effectively treat AR-PCNSL, achieving long-term survival with few relapses. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that short-term HD-MTX monochemotherapy improves long-term survival of patients with AIDS with primary CNS lymphoma receiving cARTs.

Wilson disease: brain pathology.

In Wilson disease (WD), brain cellular damage is thought to be due to copper deposition. Striatal lesions are the most characteristic lesions found in the brain of patients with neurologic symptoms, as emphasized in the initial reports of S.A.K. Wilson. WD brain lesions can be more diffuse, including in the pons, midbrain, thalamus, dentate nucleus, and, less frequently, corpus callosum and cortex. In rare cases, extensive cortical-subcortical lesions have been reported. Increased cellularity is noted in the lesions due to the proliferation of modified astrocytes named Alzheimer types of glia and specific cells, called Opalski cells, that are characteristic of WD. Although abnormalities in the putamen predominate in patients with dystonic syndrome, clinicopathologic correlations are scarce. Furthermore, the cerebral copper content is not correlated with the severity of the neuropathologic abnormalities or with the neuropsychiatric symptomatology. This fact raises the question of factors other than copper toxicity that may contribute to the pathogenesis of WD neurologic disturbances.

Quiescin-sulfhydryl oxidase inhibits prion formation in vitro.

Prions are infectious proteins that cause a group of fatal transmissible diseases in animals and humans. The scrapie isoform (PrPSc) of the cellular prion protein (PrPC) is the only known component of the prion. Several lines of evidence have suggested that the formation and molecular features of PrPSc are associated with an abnormal unfolding/refolding process. Quiescin-sulfhydryl oxidase (QSOX) plays a role in protein folding by introducing disulfides into unfolded reduced proteins. Here we report that QSOX inhibits human prion propagation in protein misfolding cyclic amplification reactions and murine prion propagation in scrapie-infected neuroblastoma cells. Moreover, QSOX preferentially binds PrPSc from prion-infected human or animal brains, but not PrPC from uninfected brains. Surface plasmon resonance of the recombinant mouse PrP (moPrP) demonstrates that the affinity of QSOX for monomer is significantly lower than that for octamer (312 nM vs 1.7 nM). QSOX exhibits much lower affinity for N-terminally truncated moPrP (PrP89-230) than for the full-length moPrP (PrP23-231) (312 nM vs 2 nM), suggesting that the N-terminal region of PrP is critical for the interaction of PrP with QSOX. Our study indicates that QSOX may play a role in prion formation, which may open new therapeutic avenues for treating prion diseases.

Transmission of scrapie prions to primate after an extended silent incubation period.

Classical bovine spongiform encephalopathy (c-BSE) is the only animal prion disease reputed to be zoonotic, causing variant Creutzfeldt-Jakob disease (vCJD) in humans and having guided protective measures for animal and human health against animal prion diseases. Recently, partial transmissions to humanized mice showed that the zoonotic potential of scrapie might be similar to c-BSE. We here report the direct transmission of a natural classical scrapie isolate to cynomolgus macaque, a highly relevant model for human prion diseases, after a 10-year silent incubation period, with features similar to those reported for human cases of sporadic CJD. Scrapie is thus actually transmissible to primates with incubation periods compatible with their life expectancy, although fourfold longer than BSE. Long-term experimental transmission studies are necessary to better assess the zoonotic potential of other prion diseases with high prevalence, notably Chronic Wasting Disease of deer and elk and atypical/Nor98 scrapie.

Evaluation of the protection of primates transfused with variant Creutzfeldt-Jakob disease-infected blood products filtered with prion removal devices: a 5-year update.

BACKGROUND: Analysis of archived appendix samples reveals that one in 2000 individuals in the United Kingdom may carry the infectious prion protein associated with variant Creutzfeldt-Jakob disease (vCJD), raising questions about the risk of transfusion transmission from apparently healthy carriers. Blood leukoreduction shows limited efficiency against prions. Therefore, in absence of antemortem diagnostic tests, prion removal filters, including the P-Capt filter were designed to improve blood transfusion safety. STUDY DESIGN AND METHODS: We evaluated the performances of two filters, the P-Capt and one prototype (PMC#005), with blood-borne infectivity in two independent experiments. Blood was drawn twice from prion-infected macaques. Corresponding RBCCs were prepared according to two different procedures: in Study A, the leukoreduction step was followed by the filtration through the P-Capt. In Study B, the leukoreduction and prion removal were performed simultaneously through the PMC#005. For each study, two groups of three animals were transfused twice with samples before or after filtration. RESULTS: Among the six macaques transfused with nonfiltered samples, five developed neurologic signs but only four exhibited peripheral detectable protease-resistant prion protein (PrPres) accumulation. In Study A, the three animals transfused with P-Capt-filtered samples remain asymptomatic and devoid of PrPres in lymph node biopsies 6 years after the transfusion. In Study B, one animal transfused with PMC#005-filtered samples developed vCJD. CONCLUSION: After 5 to 6 years of progress, this ongoing study provides encouraging results on the prion blood removal performances of the P-Capt filter in macaques, an utmost relevant model for human prion diseases.

Comparative Study of Prions in Iatrogenic and Sporadic Creutzfeldt-Jakob Disease.

Differentiating iatrogenic Creutzfeldt-Jakob disease (iCJD) from sporadic CJD (sCJD) would be useful for the identification and prevention of human-to-human prion transmission. Currently, the diagnosis of iCJD depends on identification of a recognized source of contamination to which patients have been exposed, in addition to fulfilling basic requirements for the establishment of diagnosis of CJD. Attempts to identify differences in clinical manifestations, neuropathological changes and pathological prion protein (PrPSc) between iCJD and sCJD have been unsuccessful. In the present study, using a variety of more sophisticated methods including sucrose step gradient sedimentation, conformational stability immunoassay, protein misfolding cyclic amplification (PMCA), fragment-mapping, and transmission study, we show no significant differences in gel profiles, oligomeric state, conformational stability and infectivity of PrPSc between iCJD and sCJD. However, using PMCA, we find that convertibility and amplification efficiency of PrPSc is greater in iCJD than in sCJD in a polymorphism-dependent manner. Moreover, two protease-resistant PrP C-terminal fragments (termed PrP-CTF12/13) were detected in all 9 cases of sCJD but not in 6 of 8 cases of iCJD tested in this study. The use of fragment mapping- and PMCA-based assays thus provides a means to distinguish most cases of iCJD from sCJD.

Isolated III cranial nerve palsies may point to primary histiocytic sarcoma.

Primary histiocytic sarcoma (HS) of the central nervous system (CNS) is a rare haematopoietic neoplasm. The inconsistent terminology and diagnostic criteria currently used for CNS HS have complicated the appreciation of the clinical aspects of the disease. The main differential diagnoses are non-Hodgkin's lymphoma, reactive histiocytic proliferation, dendritic cell neoplasm, undifferentiated carcinoma, inflammatory pseudotumour, Rosai-Dorfman disease and abscess. The true diagnosis of CNS HS requires an extensive immunophenotypic workup using specific histiocytic markers, such as CD163, with the exclusion of markers of other cell lineages. This clinicopathological case report describes an improved approach towards the differential diagnosis of CNS HS.

Recombinant human prion protein inhibits prion propagation in vitro.

Prion diseases are associated with the conformational conversion of the cellular prion protein (PrP(C)) into the pathological scrapie isoform (PrP(Sc)) in the brain. Both the in vivo and in vitro conversion of PrP(C) into PrP(Sc) is significantly inhibited by differences in amino acid sequence between the two molecules. Using protein misfolding cyclic amplification (PMCA), we now report that the recombinant full-length human PrP (rHuPrP23-231) (that is unglycosylated and lacks the glycophosphatidylinositol anchor) is a strong inhibitor of human prion propagation. Furthermore, rHuPrP23-231 also inhibits mouse prion propagation in a scrapie-infected mouse cell line. Notably, it binds to PrP(Sc), but not PrP(C), suggesting that the inhibitory effect of recombinant PrP results from blocking the interaction of brain PrP(C) with PrP(Sc). Our findings suggest a new avenue for treating prion diseases, in which a patient's own unglycosylated and anchorless PrP is used to inhibit PrP(Sc) propagation without inducing immune response side effects.