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Synucleinopathies, including Parkinson's disease (PD), multiple system atrophy (MSA), and dementia with Lewy bodies (DLB), are neurodegenerative disorders caused by the accumulation of misfolded alpha-synuclein protein. Developing effective vaccines against synucleinopathies is challenging due to the difficulty of stimulating an immune-specific response against alpha-synuclein without causing harmful autoimmune reactions, selectively targeting only pathological forms of alpha-synuclein. Previous attempts using linear peptides and epitopes without control of the antigen structure failed in clinical trials. The immune system was unable to distinguish between native alpha-synuclein and its amyloid form. The prion domain of the fungal HET-s protein was selected as a scaffold to introduce select epitopes from the surface of alpha-synuclein fibrils. Four vaccine candidates were generated by introducing specific amino acid substitutions onto the surface of the scaffold protein. The approach successfully mimicked the stacking of the parallel in-register beta-sheet structure seen in alpha-synuclein fibrils. All vaccine candidates induced substantial levels of IgG antibodies that recognized pathological alpha-synuclein fibrils derived from a synucleinopathy mouse model. Furthermore, the antisera recognized pathological alpha-synuclein aggregates in brain lysates from patients who died from DLB, MSA, or PD, but did not recognize linear alpha-synuclein peptides. Our approach, based on the rational design of vaccines using the structure of alpha-synuclein amyloid fibrils and strict control over the exposed antigen structure used for immunization, as well as the ability to mimic aggregated alpha-synuclein, provides a promising avenue toward developing effective vaccines against alpha-synuclein fibrils.
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While several functions of the endogenous prion protein (PrP) have been studied, the homeostatic function of PrP is still debated. Notably, PrP is highly expressed on mast cells, granular immune cells that regulate inflammation. When activated, mast cells shed PrP though the mechanism and consequences of this are not yet understood. First, we tested several mast cell lines and found that, while PrP was almost always present, the total amount differed greatly. Activation of mast cells induced a cleavage of the N-terminal region of PrP, and this was reduced by protease inhibitors. Exogenous mast cell proteases caused a similar loss of the PrP N-terminus. Additionally, mast cells shed PrP in an ADAM10-dependent fashion even in the absence of activation. Our results suggest that PrP is cleaved from resting mast cells by ADAM10 and from activated mast cells by mast cell proteases. PrP also appears to affect mast cell function, as Prnp-/- BMMC showed lower levels of degranulation and cytokine release, as well as lower levels of both FcεRI and CD117. Finally, we sought to provide clinical relevance by measuring the levels of PrP in bodily fluids of asthmatic patients, a disease that involves the activation of mast cells. We found an N-terminal fragment of PrP could be detected in human sputum and serum and the amount of this PrP fragment was decreased in the serum of patients with asthma.
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Microglia play diverse pathophysiological roles in Alzheimer's disease (AD), with genetic susceptibility factors skewing microglial cell function to influence AD risk. CD33 is an immunomodulatory receptor associated with AD susceptibility through a single nucleotide polymorphism that modulates mRNA splicing, skewing protein expression from a long protein isoform (CD33M) to a short isoform (CD33m). Understanding how human CD33 isoforms differentially impact microglial cell function in vivo has been challenging due to functional divergence of CD33 between mice and humans. We address this challenge by studying transgenic mice expressing either of the human CD33 isoforms crossed with the 5XFAD mouse model of amyloidosis and find that human CD33 isoforms have opposing effects on the response of microglia to amyloid-ß (Aß) deposition. Mice expressing CD33M have increased Aß levels, more diffuse plaques, fewer disease-associated microglia, and more dystrophic neurites compared to 5XFAD control mice. Conversely, CD33m promotes plaque compaction and microglia-plaque contacts, and minimizes neuritic plaque pathology, highlighting an AD protective role for this isoform. Protective phenotypes driven by CD33m are detected at an earlier timepoint compared to the more aggressive pathology in CD33M mice that appears at a later timepoint, suggesting that CD33m has a more prominent impact on microglia cell function at earlier stages of disease progression. In addition to divergent roles in modulating phagocytosis, scRNAseq and proteomics analyses demonstrate that CD33m+ microglia upregulate nestin, an intermediate filament involved in cell migration, at plaque contact sites. Overall, our work provides new functional insights into how CD33, as a top genetic susceptibility factor for AD, modulates microglial cell function.
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Doença de Alzheimer , Modelos Animais de Doenças , Camundongos Transgênicos , Microglia , Isoformas de Proteínas , Lectina 3 Semelhante a Ig de Ligação ao Ácido Siálico , Animais , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Microglia/metabolismo , Lectina 3 Semelhante a Ig de Ligação ao Ácido Siálico/metabolismo , Humanos , Camundongos , Isoformas de Proteínas/metabolismo , Peptídeos beta-Amiloides/metabolismo , Placa Amiloide/metabolismo , Placa Amiloide/patologiaRESUMO
A distinctive signature of the prion diseases is the accumulation of the pathogenic isoform of the prion protein, PrPSc, in the central nervous system of prion-affected humans and animals. PrPSc is also found in peripheral tissues, raising concerns about the potential transmission of pathogenic prions through human food supplies and posing a significant risk to public health. Although muscle tissues are considered to contain levels of low prion infectivity, it has been shown that myotubes in culture efficiently propagate PrPSc. Given the high consumption of muscle tissue, it is important to understand what factors could influence the establishment of a prion infection in muscle tissue. Here we used in vitro myotube cultures, differentiated from the C2C12 myoblast cell line (dC2C12), to identify factors affecting prion replication. A range of experimental conditions revealed that PrPSc is tightly associated with proteins found in the systemic extracellular matrix, mostly fibronectin (FN). The interaction of PrPSc with FN decreased prion infectivity, as determined by standard scrapie cell assay. Interestingly, the prion-resistant reserve cells in dC2C12 cultures displayed a FN-rich extracellular matrix while the prion-susceptible myotubes expressed FN at a low level. In agreement with the in vitro results, immunohistopathological analyses of tissues from sheep infected with natural scrapie demonstrated a prion susceptibility phenotype linked to an extracellular matrix with undetectable levels of FN. Conversely, PrPSc deposits were not observed in tissues expressing FN. These data indicate that extracellular FN may act as a natural barrier against prion replication and that the extracellular matrix composition may be a crucial feature determining prion tropism in different tissues.
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Fibronectinas , Doenças Priônicas , Príons , Scrapie , Animais , Humanos , Linhagem Celular , Fibronectinas/uso terapêutico , Doenças Priônicas/tratamento farmacológico , Doenças Priônicas/prevenção & controle , Príons/metabolismo , Scrapie/metabolismo , OvinosRESUMO
IgE Abs, best known for their role in allergic reactions, have only rarely been used in immunotherapies. Nevertheless, they offer a potential alternative to the more commonly used IgGs. The affinity of IgE Ag binding influences the type of response from mast cells, so any immunotherapies using IgEs must balance Ag affinity with desired therapeutic effect. One potential way to harness differential binding affinities of IgE is in protein aggregation diseases, where low-affinity binding of endogenous proteins is preferred, but enhanced binding of clusters of disease-associated aggregated proteins could target responses to the sites of disease. For this reason, we sought to create a low-affinity IgE against the prion protein (PrP), which exists in an endogenous monomeric state but can misfold into aggregated states during the development of prion disease. First, we determined that mast cell proteases tryptase and cathepsin G were capable of degrading PrP. Then we engineered a recombinant IgE Ab directed against PrP from the V region of a PrP-specific IgG and tested its activation of the human mast cell line LAD2. The αPrP IgE bound LAD2 through Fc receptors. Crosslinking receptor-bound αPrP IgE activated SYK and ERK phosphorylation, caused Fc receptor internalization, and resulted in degranulation. This work shows that a recombinant αPrP IgE can activate LAD2 cells to release enzymes that can degrade PrP, suggesting that IgE may be useful in targeting diseases that involve protein aggregation.
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Proteínas Priônicas , Receptores de IgE , Humanos , Receptores de IgE/metabolismo , Proteínas Priônicas/metabolismo , Mastócitos/metabolismo , Peptídeo Hidrolases/metabolismo , Agregados Proteicos , Imunoglobulina E/metabolismo , Degranulação CelularRESUMO
Prion diseases are fatal neurodegenerative diseases caused by pathogenic misfolding of the prion protein, PrP. They are transmissible between hosts, and sometimes between different species, as with transmission of bovine spongiform encephalopathy to humans. Although PrP is found in a wide range of vertebrates, prion diseases are seen only in certain mammals, suggesting that infectious misfolding was a recent evolutionary development. To explore when PrP acquired the ability to misfold infectiously, we reconstructed the sequences of ancestral versions of PrP from the last common primate, primate-rodent, artiodactyl, placental, bird, and amniote. Recombinant ancestral PrPs were then tested for their ability to form ß-sheet aggregates, either spontaneously or when seeded with infectious prion strains from human, cervid, or rodent species. The ability to aggregate developed after the oldest ancestor (last common amniote), and aggregation capabilities diverged along evolutionary pathways consistent with modern-day susceptibilities. Ancestral bird PrP could not be seeded with modern-day prions, just as modern-day birds are resistant to prion disease. Computational modeling of structures suggested that differences in helix 2 could account for the resistance of ancestral bird PrP to seeding. Interestingly, ancestral primate PrP could be converted by all prion seeds, including both human and cervid prions, raising the possibility that species descended from an ancestral primate have retained the susceptibility to conversion by cervid prions. More generally, the results suggest that susceptibility to prion disease emerged prior to ~100 million years ago, with placental mammals possibly being generally susceptible to disease.
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Doenças Priônicas , Príons , Gravidez , Animais , Bovinos , Feminino , Humanos , Proteínas Priônicas/química , Placenta/metabolismo , Príons/metabolismo , Doenças Priônicas/genética , Doenças Priônicas/metabolismo , MamíferosRESUMO
Amyloid ß (Aß) peptides generated from the amyloid precursor protein (APP) play a critical role in the development of Alzheimer's disease (AD) pathology. Aß-containing neuronal exosomes, which represent a novel form of intercellular communication, have been shown to influence the function/vulnerability of neurons in AD. Unlike neurons, the significance of exosomes derived from astrocytes remains unclear. In this study, we evaluated the significance of exosomes derived from U18666A-induced cholesterol-accumulated astrocytes in the development of AD pathology. Our results show that cholesterol accumulation decreases exosome secretion, whereas lowering cholesterol increases exosome secretion, from cultured astrocytes. Interestingly, exosomes secreted from U18666A-treated astrocytes contain higher levels of APP, APP-C-terminal fragments, soluble APP, APP secretases and Aß1-40 than exosomes secreted from control astrocytes. Furthermore, we show that exosomes derived from U18666A-treated astrocytes can lead to neurodegeneration, which is attenuated by decreasing Aß production or by neutralizing exosomal Aß peptide with an anti-Aß antibody. These results, taken together, suggest that exosomes derived from cholesterol-accumulated astrocytes can play an important role in trafficking APP/Aß peptides and influencing neuronal viability in the affected regions of the AD brain.
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Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Astrócitos/metabolismo , Colesterol/metabolismo , Exossomos/metabolismo , Peptídeos beta-Amiloides/metabolismo , Androstenos/farmacologia , Animais , Astrócitos/efeitos dos fármacos , Astrócitos/ultraestrutura , Autofagia/efeitos dos fármacos , Catepsina D/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Exossomos/efeitos dos fármacos , Exossomos/ultraestrutura , Feminino , Proteína 1 de Membrana Associada ao Lisossomo , Lisossomos/efeitos dos fármacos , Lisossomos/metabolismo , Lisossomos/ultraestrutura , Camundongos Endogâmicos BALB C , Proteínas Associadas aos Microtúbulos , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , RatosRESUMO
Prion diseases are transmissible neurodegenerative disorders that affect mammals, including humans. The central molecular event is the conversion of cellular prion glycoprotein, PrPC, into a plethora of assemblies, PrPSc, associated with disease. Distinct phenotypes of disease led to the concept of prion strains, which are associated with distinct PrPSc structures. However, the degree to which intra- and inter-strain PrPSc heterogeneity contributes to disease pathogenesis remains unclear. Addressing this question requires the precise isolation and characterization of all PrPSc subpopulations from the prion-infected brains. Until now, this has been challenging. We used asymmetric-flow field-flow fractionation (AF4) to isolate all PrPSc subpopulations from brains of hamsters infected with three prion strains: Hyper (HY) and 263K, which produce almost identical phenotypes, and Drowsy (DY), a strain with a distinct presentation. In-line dynamic and multi-angle light scattering (DLS/MALS) data provided accurate measurements of particle sizes and estimation of the shape and number of PrPSc particles. We found that each strain had a continuum of PrPSc assemblies, with strong correlation between PrPSc quaternary structure and phenotype. HY and 263K were enriched with large, protease-resistant PrPSc aggregates, whereas DY consisted primarily of smaller, more protease-sensitive aggregates. For all strains, a transition from protease-sensitive to protease-resistant PrPSc took place at a hydrodynamic radius (Rh) of 15 nm and was accompanied by a change in glycosylation and seeding activity. Our results show that the combination of AF4 with in-line MALS/DLS is a powerful tool for analyzing PrPSc subpopulations and demonstrate that while PrPSc quaternary structure is a major contributor to PrPSc structural heterogeneity, a fundamental change, likely in secondary/tertiary structure, prevents PrPSc particles from maintaining proteinase K resistance below an Rh of 15 nm, regardless of strain. This results in two biochemically distinctive subpopulations, the proportion, seeding activity, and stability of which correlate with prion strain phenotype.
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Difusão Dinâmica da Luz/métodos , Fotometria/métodos , Proteínas PrPSc/análise , Proteínas PrPSc/química , Animais , Cricetinae , Hidrodinâmica , Camundongos , Estrutura Quaternária de ProteínaRESUMO
Sporadic Creutzfeldt-Jakob Disease (sCJD) rarely affects women of childbearing age. There is currently no evidence of vertical transmission. Given the biosafety implications of performing Caesarean sections (C-section) in these patients, we used sensitive real-time quaking-induced conversion (RT-QuIC) assays to test for the infectious prion protein (PrPSc) in products of gestation. A 35-year-old woman with sCJD presented in her 10th gestational week with an eight month history of progressive cognitive impairment. During C-section, amniotic fluid, cord blood and placental tissue were collected and analysed using RT-QuIC protocols adapted for use with these tissues. The patient's diagnosis of sCJD, MM2 subtype, was confirmed at autopsy. There were borderline positive results in one sampled area of the placenta, but otherwise the cord blood and amniotic fluid were negative on our RT-QuIC assays. A healthy baby was delivered via C-section at 36 weeks and 3 days gestational age, with no evidence of neurological disease to date. We conclude that precautions should be taken with products of gestation, but the level of PrPSc is extremely low.
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Síndrome de Creutzfeldt-Jakob , Príons , Adulto , Bioensaio , Feminino , Humanos , Placenta , Gravidez , Proteínas PriônicasRESUMO
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.
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Proteína ADAM10 , Encéfalo , Glicoproteínas de Membrana , Doenças Priônicas , Receptores Imunológicos , Proteína ADAM10/sangue , Proteína ADAM10/líquido cefalorraquidiano , Proteína ADAM10/metabolismo , Doença de Alzheimer/metabolismo , Animais , Biomarcadores/metabolismo , Encéfalo/metabolismo , Modelos Animais de Doenças , Humanos , Glicoproteínas de Membrana/sangue , Glicoproteínas de Membrana/líquido cefalorraquidiano , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/metabolismo , Camundongos , Microglia/metabolismo , Doenças Priônicas/genética , Doenças Priônicas/metabolismo , Doenças Priônicas/patologia , Proteínas Priônicas/metabolismo , Receptores Imunológicos/sangue , Receptores Imunológicos/genética , Receptores Imunológicos/metabolismoRESUMO
Prion diseases are fatal, infectious, and incurable neurodegenerative disorders caused by misfolding of the cellular prion protein (PrPC) into the infectious isoform (PrPSc). In humans, there are sporadic, genetic and infectious etiologies, with sporadic Creutzfeldt-Jakob disease (sCJD) being the most common form. Currently, no treatment is available for prion diseases. Cellular cholesterol is known to impact prion conversion, which in turn results in an accumulation of cholesterol in prion-infected neurons. The major elimination of brain cholesterol is achieved by the brain specific enzyme, cholesterol 24-hydroxylase (CYP46A1). Cyp46A1 converts cholesterol into 24(S)-hydroxycholesterol, a membrane-permeable molecule that exits the brain. We have demonstrated for the first time that Cyp46A1 levels are reduced in the brains of prion-infected mice at advanced disease stage, in prion-infected neuronal cells and in post-mortem brains of sCJD patients. We have employed the Cyp46A1 activator efavirenz (EFV) for treatment of prion-infected neuronal cells and mice. EFV is an FDA approved anti-HIV medication effectively crossing the blood brain barrier and has been used for decades to chronically treat HIV patients. EFV significantly mitigated PrPSc propagation in prion-infected cells while preserving physiological PrPC and lipid raft integrity. Notably, oral administration of EFV treatment chronically at very low dosage starting weeks to months after intracerebral prion inoculation of mice significantly prolonged the lifespan of animals. In summary, our results suggest that Cyp46A1 as a novel therapeutic target and that its activation through repurposing the anti-retroviral medication EFV might be valuable treatment approach for prion diseases.
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Alcinos/farmacologia , Benzoxazinas/farmacologia , Colesterol 24-Hidroxilase/metabolismo , Síndrome de Creutzfeldt-Jakob/metabolismo , Ciclopropanos/farmacologia , Inibidores das Enzimas do Citocromo P-450/farmacologia , Proteínas PrPSc/efeitos dos fármacos , Administração Oral , Animais , Colesterol 24-Hidroxilase/efeitos dos fármacos , Reposicionamento de Medicamentos , Humanos , Microdomínios da Membrana/metabolismo , Camundongos , Proteínas PrPC/efeitos dos fármacos , Proteínas PrPC/metabolismo , Proteínas PrPSc/metabolismoRESUMO
Prion diseases are the hallmark protein folding neurodegenerative disease. Their transmissible nature has allowed for the development of many different cellular models of disease where prion propagation and sometimes pathology can be induced. This review examines the range of simple cell cultures to more complex neurospheres, organoid, and organotypic slice cultures that have been used to study prion disease pathogenesis and to test therapeutics. We highlight the advantages and disadvantages of each system, giving special consideration to the importance of strains when choosing a model and when interpreting results, as not all systems propagate all strains, and in some cases, the technique used, or treatment applied, can alter the very strain properties being studied.
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Técnicas de Cultura de Células , Modelos Biológicos , Organoides/metabolismo , Príons/metabolismo , Animais , Encéfalo/citologia , Humanos , Células-Tronco Pluripotentes Induzidas/citologia , Células-Tronco Pluripotentes Induzidas/metabolismoRESUMO
Prion diseases are fatal neurodegenerative diseases in mammals with the unique characteristics of misfolding and aggregation of the cellular prion protein (PrPC) to the scrapie prion (PrPSc). Although neuroinflammation and neuronal loss feature within the disease process, the details of PrPC/PrPSc molecular transition to generate different aggregated species, and the correlation between each species and sequence of cellular events in disease pathogenesis are not fully understood. In this study, using mice inoculated with the RML isolate of mouse-adapted scrapie as a model, we applied asymmetric flow field-flow fractionation to monitor PrPC and PrPSc particle sizes and we also measured seeding activity and resistance to proteases. For cellular analysis in brain tissue, we measured inflammatory markers and synaptic damage, and used the isotropic fractionator to measure neuronal loss; these techniques were applied at different timepoints in a cross-sectional study of disease progression. Our analyses align with previous reports defining significant decreases in PrPC levels at pre-clinical stages of the disease and demonstrate that these decreases become significant before neuronal loss. We also identified the earliest PrPSc assemblies at a timepoint equivalent to 40% elapsed time for the disease incubation period; we propose that these assemblies, mostly composed of proteinase K (PK)-sensitive species, play an important role in triggering disease pathogenesis. Lastly, we show that the PK-resistant assemblies of PrPSc that appear at timepoints close to the terminal stage have similar biophysical characteristics, and hence that preparative use of PK-digestion selects for this specific subpopulation. In sum, our data argue that qualitative, as well as quantitative, changes in PrP conformers occur at the midpoint of subclinical phase; these changes affect quaternary structure and may occur at the threshold where adaptive responses become inadequate to deal with pathogenic processes.
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Progressão da Doença , Regulação para Baixo , Proteínas PrPC/metabolismo , Proteínas PrPSc/química , Scrapie/patologia , Animais , Biomarcadores/metabolismo , Encéfalo/patologia , Morte Celular , Endopeptidase K/metabolismo , Proteína Glial Fibrilar Ácida/metabolismo , Inflamação/patologia , Camundongos , Peso Molecular , Proteínas PrPSc/metabolismo , Estrutura Quaternária de Proteína , Solubilidade , Sinapses/patologia , Fatores de TempoRESUMO
Creutzfeldt-Jakob disease (CJD) is a rapidly progressive neurodegenerative disease that can arise spontaneously, genetically, or be acquired through iatrogenic exposure. Most patients die within a year of symptom onset. It is rare, affecting 1-2 per million per year, and the majority of cases are sporadic. Primary angiitis of the central nervous system (PACNS) is also rare, affecting 2.4 per million per year. We present a case of an unusually long clinical course of CJD, almost five years, which began with symptoms of apraxia. The patient had biopsy-proven PACNS 16 years prior to clinical presentation, and the site of biopsy was the left parietal lobe. Autopsy revealed multicentric prion plaques in the cerebellum, in the setting of normal genetic testing. The presence of plaques in the cerebellum, and prior neurosurgery, raises the possibility of iatrogenic exposure. We present the details of this case, including pathology from the original biopsy and final autopsy, as well as a review of relevant cases in the literature.
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Cerebelo/metabolismo , Cerebelo/patologia , Síndrome de Creutzfeldt-Jakob/diagnóstico , Síndrome de Creutzfeldt-Jakob/etiologia , Príons/metabolismo , Vasculite do Sistema Nervoso Central/diagnóstico , Vasculite do Sistema Nervoso Central/etiologia , Cerebelo/diagnóstico por imagem , Síndrome de Creutzfeldt-Jakob/metabolismo , Progressão da Doença , Suscetibilidade a Doenças , Humanos , Doença Iatrogênica , Imuno-Histoquímica , Imageamento por Ressonância Magnética , Pessoa de Meia-IdadeRESUMO
The majority of human prion diseases are sporadic, but acquired disease can occur, as seen with variant Creutzfeldt-Jakob disease (vCJD) following consumption of bovine spongiform encephalopathy (BSE). With increasing rates of cervid chronic wasting disease (CWD), there is concern that a new form of human prion disease may arise. Currently, there is no evidence of transmission of CWD to humans, suggesting the presence of a strong species barrier; however, in vitro and in vivo studies on the zoonotic potential of CWD have yielded mixed results. The emergence of different CWD strains is also concerning, as different strains can have different abilities to cross species barriers. Given that venison consumption is common in areas where CWD rates are on the rise, increased rates of human exposure are inevitable. If CWD was to infect humans, it is unclear how it would present clinically; in vCJD, it was strain-typing of vCJD prions that proved the causal link to BSE. Therefore, the best way to screen for CWD in humans is to have thorough strain-typing of harvested cervids and human CJD cases so that we will be in a position to detect atypical strains or strain shifts within the human CJD population.
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Doença de Emaciação Crônica/transmissão , Zoonoses/transmissão , Animais , Predisposição Genética para Doença , Humanos , Polimorfismo Genético , Proteínas Priônicas/genética , Risco , Doença de Emaciação Crônica/diagnóstico , Doença de Emaciação Crônica/etiologia , Doença de Emaciação Crônica/genéticaRESUMO
Prion diseases are fatal, transmissible neurodegenerative disorders whose pathogenesis is driven by the misfolding, self-templating and cell-to-cell spread of the prion protein. Other neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis and Huntington's disease, share some of these prion-like features, with different aggregation-prone proteins. Consequently, researchers have begun to apply prion-specific techniques, like the prion organotypic slice culture assay (POSCA), to these disorders. In this review we explore the ways in which the prion phenomenon has been used in organotypic cultures to study neurodegenerative diseases from the perspective of protein aggregation and spreading, strain propagation, the role of glia in pathogenesis, and efficacy of drug treatments. We also present an overview of the advantages and disadvantages of this culture system compared to in vivo and in vitro models and provide suggestions for new directions.
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Doenças Neurodegenerativas/patologia , Técnicas de Cultura de Órgãos/métodos , Doenças Priônicas/patologia , Príons/análise , Animais , Pesquisa Biomédica/métodos , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Encéfalo/patologia , Avaliação Pré-Clínica de Medicamentos/métodos , Humanos , Doenças Neurodegenerativas/tratamento farmacológico , Doenças Neurodegenerativas/metabolismo , Doenças Priônicas/tratamento farmacológico , Doenças Priônicas/metabolismo , Príons/metabolismo , Agregação Patológica de Proteínas/tratamento farmacológico , Agregação Patológica de Proteínas/metabolismo , Agregação Patológica de Proteínas/patologiaRESUMO
OBJECTIVE: A literature review was conducted to identify available evidence on the use of multimedia patient educational interventions on anticoagulation therapy. METHODS: A literature search was conducted on 9/4/2020 via six research databases. Publications that evaluated the effects of these interventions on anticoagulation therapy were included. RESULTS: The review included ten original research studies (five randomized controlled trials, four observational studies and a pre- and post-interventional study), a systematic review and meta-analysis, three systematic reviews, a scoping review, and a literature review. Multimedia interventions significantly improved knowledge after education, but no significant differences found when compared to traditional methods. There was insufficient evidence to conclude whether knowledge retained over time. Patients were equally satisfied with both methods. Multimedia interventions significantly reduced healthcare professional's time required for education. Heterogeneity in intervention, methodology and results limited comparison and combination of findings across studies. CONCLUSION: Multimedia patient educational interventions on anticoagulation therapy have similar outcomes to traditional methods in knowledge improvement and satisfaction, but they save health personnel time. PRACTICE IMPLICATIONS: There is lack of evidence to support the effectiveness of multimedia interventions in educating patients on anticoagulation therapy. Larger randomized studies evaluating their benefits in health outcomes and clinical practice are warranted.
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Anticoagulantes/uso terapêutico , Multimídia , Educação de Pacientes como Assunto , Anticoagulantes/efeitos adversos , Pessoal de Saúde , Humanos , ConhecimentoRESUMO
One of remarkable features of sporadic Creutzfeldt-Jakob disease (sCJD) is the great phenotypic variability. Understanding the molecular basis of this variability has important implications for the development of therapeutic approaches. It is well established that, in many cases, phenotypic heterogeneity of sCJD is under control of two determinants: the genotype at the methionine (M)/valine (V) polymorphic codon 129 of the human prion protein gene and the type, 1 or 2, of the pathogenic and disease-related form of the prion protein, PrPD. However, this scenario fails to explain the existence of distinct heterozygous sCJDMV2 subtypes, where heterogeneity occurs without any variation of the 129 allotype and PrPD type. One of these subtypes, denoted sCJDMV2C, associated with PrPD type 2, is characterized by widespread spongiform degeneration of the cerebral cortex (C). The second variant, denoted sCJDMV2K, features prominent deposition of PrPD amyloid forming kuru type (K) plaques. Here we used a mass spectrometry based approach to test the hypothesis that phenotypic variability within the sCJDMV2 subtype is at least partly determined by the abundance of 129 M and 129 V polymorphic forms of proteinase K-resistant PrPD (resPrPD). Consistent with this hypothesis, our data demonstrated a strong correlation of the MV2C and MV2K phenotypes with the relative populations of protease-resistant forms of the pathogenic prion proteins, resPrPD-129 M and resPrPD-129 V, where resPrPD-129 M dominated in the sCJDMV2C variant and resPrPD-129 V in the sCJDMV2K variant. This finding suggests an important, previously unrecognized mechanism for phenotypic determination in human prion diseases.
Assuntos
Síndrome de Creutzfeldt-Jakob/metabolismo , Síndrome de Creutzfeldt-Jakob/patologia , Proteínas Priônicas/metabolismo , Cerebelo/metabolismo , Cerebelo/patologia , Córtex Cerebral/metabolismo , Córtex Cerebral/patologia , Mapeamento de Epitopos , Humanos , Espectrometria de Massas , Metionina/química , Fenótipo , Proteínas Priônicas/química , Valina/químicaRESUMO
Prions are lipidated proteins that interact with endogenous lipids and metal ions. They also assemble into multimers and propagate into the infectious scrapie form known as PrPSc The high-resolution structure of the infectious PrPSc state remains unknown, and its analysis largely relies on detergent-based preparations devoid of endogenous ligands. Here we designed polymers that allow isolation of endogenous membrane:protein assemblies in native nanodiscs without exposure to conventional detergents that destabilize protein structures and induce fibrillization. A set of styrene-maleic acid (SMA) polymers including a methylamine derivative facilitated gentle release of the infectious complexes for resolution of multimers, and a thiol-containing version promoted crystallization. Polymer extraction from brain homogenates from Syrian hamsters infected with Hyper prions and WT mice infected with Rocky Mountain Laboratories prions yielded infectious prion nanoparticles including oligomers and microfilaments bound to lipid vesicles. Lipid analysis revealed the brain phospholipids that associate with prion protofilaments, as well as those that are specifically enriched in prion assemblies captured by the methylamine-modified copolymer. A comparison of the infectivity of PrPSc attached to SMA lipid particles in mice and hamsters indicated that these amphipathic polymers offer a valuable tool for high-yield production of intact, detergent-free prions that retain in vivo activity. This native prion isolation method provides an avenue for producing relevant prion:lipid targets and potentially other proteins that form multimeric assemblies and fibrils on membranes.