Marco Sbriccoli

Chronic wasting disease and atypical forms of bovine spongiform encephalopathy and scrapie are not transmissible to mice expressing wild-type levels of human prion protein

The association between bovine spongiform encephalopathy (BSE) and variant Creutzfeldt-Jakob disease (vCJD) has demonstrated that cattle transmissible spongiform encephalopathies (TSEs) can pose a risk to human health and raises the possibility that other ruminant TSEs may be transmissible to humans. In recent years, several novel TSEs in sheep, cattle and deer have been described and the risk posed to humans by these agents is currently unknown. In this study, we inoculated two forms of atypical BSE (BASE and H-type BSE), a chronic wasting disease (CWD) isolate and seven isolates of atypical scrapie into gene-targeted transgenic (Tg) mice expressing the human prion protein (PrP). Upon challenge with these ruminant TSEs, gene-targeted Tg mice expressing human PrP did not show any signs of disease pathology. These data strongly suggest the presence of a substantial transmission barrier between these recently identified ruminant TSEs and humans.

Migration of dendritic cells into the brain in a mouse model of prion disease.

The immune system plays a key role in the dissemination of prion infections from the periphery to the central nervous system (CNS). While follicular dendritic cells are critical for prion replication in lymphoid tissue and subsequent neuroinvasion, myeloid dendritic cells (DCs) have been implicated in both the clearance and propagation of pathological prion protein. Since nothing is known on the ability of DCs to migrate to the CNS during prion diseases, we investigated the immunohistochemical localization of CD205(+) DCs in the brain of C57BL/6 mice intraperitoneally infected with the mouse-adapted KFu strain of Gerstmann-Sträussler-Scheinker syndrome, a human genetic prion disorder. In normal brain, CD205(+) cells were present in the meninges and choroid plexus, whereas in the majority of mice sacrificed between 120 and 300 days post infection, CD205(+) DCs were also detected in the cerebral cortex, subcortical white matter, thalamus and medulla oblongata. These findings demonstrate that DCs can enter the CNS of prion-infected mice, suggesting a possible role for these cells in the pathogenesis of prion disorders.

Comparison of nanofiltration efficacy in reducing infectivity of centrifuged versus ultracentrifuged 263K scrapie‐infected brain homogenates in “spiked” albumin solutions

BACKGROUND: The safety of plasma‐derived products is of concern for possible transmission of variant Creutzfeldt‐Jakob disease. The absence of validated screening tests requires the use of procedures to remove or inactivate prions during the manufacture of plasma‐derived products to minimize the risk of transmission. These procedures need proper validation studies based on spiking human plasma or intermediate fractions of plasma fractionation with prions in a form as close as possible to that present in blood.

Assessment of prion reduction filters in decreasing infectivity of ultracentrifuged 263K scrapie-infected brain homogenates in "spiked" human blood and red blood cells.

The safety of red blood cells (RBCs) is of concern because of the occurrence of four transfusion‐transmitted variant Creutzfeldt‐Jakob disease (vCJD) cases in the United Kingdom. The absence of validated screening tests requires the use of procedures to remove prions from blood to minimize the risk of transmission. These procedures must be validated using infectious prions in a form that is as close as possible to one in blood.

Different Prion Conformers Target the Olfactory Pathway in Sporadic Creutzfeldt–Jakob Disease

Prion diseases, or transmissible spongiform encephalopathies (TSEs), are mammalian neurodegenerative diseases that occur as sporadic, inherited, or iatrogenic forms. Human TSEs exhibit a wide spectrum of phenotypic variability, which is influenced by (1) the conformation of the pathologic prion protein, or PrPSc; (2) the polymorphic codon 129 of the prion protein gene (PRNP), involving synonymous or nonsynonymous expression of Met or Val; and (3) the site of formation or entry of the self‐replicating PrPSc. Brain deposition of PrPSc occurs in a phenotype‐specific regional pattern, either as extracellular amyloid plaques and plaque‐like aggregates, or as fine granular immunoreactivity at intracellular sites and presynaptic and postsynaptic locations, including dendrites. We previously demonstrated PrPSc deposition in ciliated dendrites of olfactory sensory neurons in sporadic Creutzfeldt–Jakob disease (sCJD), the most common human prion disease. PrPSc immunoreactivity was not limited to the olfactory neuroepithelium. But additionally involved the central olfactory pathway. More recently, we have found that the pathology of the olfactory pathway occurs early in the disease course, either in the myoclonic or classic sCJD or in the ataxic variant. Intriguingly, in the ataxic or cerebellar variant, mainly observed in patients with the Met/Val polymorphism (2) carrying PrPSc type 2, olfactory involvement is accompanied by pathologic changes in the dorsal motor nucleus of the vagus and other brainstem nuclei. These findings suggest that different molecular events and distinct routes of PrPSc spread contribute to the prominent heterogeneity of sCJD, conceivably providing support to the olfactory pathogenesis theory of neurodegenerative diseases.

Prion Strain Characterization of a Novel Subtype of Creutzfeldt-Jakob Disease

ABSTRACT In 2007, we reported a patient with an atypical form of Creutzfeldt-Jakob disease (CJD) heterozygous for methionine-valine (MV) at codon 129 who showed a novel pathological prion protein (PrPTSE) conformation with an atypical glycoform (AG) profile and intraneuronal PrP deposition. In the present study, we further characterize the conformational properties of this pathological prion protein (PrPTSE MVAG), showing that PrPTSE MVAG is composed of multiple conformers with biochemical properties distinct from those of PrPTSE type 1 and type 2 of MV sporadic CJD (sCJD). Experimental transmission of CJD-MVAG to bank voles and gene-targeted transgenic mice carrying the human prion protein gene (TgHu mice) showed unique transmission rates, survival times, neuropathological changes, PrPTSE deposition patterns, and PrPTSE glycotypes that are distinct from those of sCJD-MV1 and sCJD-MV2. These biochemical and experimental data suggest the presence of a novel prion strain in CJD-MVAG. IMPORTANCE Sporadic Creutzfeldt-Jakob disease is caused by the misfolding of the cellular prion protein, which assumes two different major conformations (type 1 and type 2) and, together with the methionine/valine polymorphic codon 129 of the prion protein gene, contribute to the occurrence of distinct clinical-pathological phenotypes. Inoculation in laboratory rodents of brain tissues from the six possible combinations of pathological prion protein types with codon 129 genotypes results in the identification of 3 or 4 strains of prions. We report on the identification of a novel strain of Creutzfeldt-Jakob disease isolated from a patient who carried an abnormally glycosylated pathological prion protein. This novel strain has unique biochemical characteristics, does not transmit to humanized transgenic mice, and shows exclusive transmission properties in bank voles. The identification of a novel human prion strain improves our understanding of the pathogenesis of the disease and of possible mechanisms of prion transmission.

PrpTSE in muscle-associated lymphatic tissue during the preclinical stage of mice infected orally with bovine spongiform encephalopathy

The involvement of muscles in the pathogenesis of transmissible spongiform encephalopathies (TSEs) is irregular and unpredictable. We show that the TSE-specific protein (PrP(TSE)) is present in muscles of mice fed with a mouse-adapted strain of bovine spongiform encephalopathy as early as 100 days post-infection, corresponding to about one-third of the incubation period. The proportion of mice with PrP(TSE)-positive muscles and the number of muscles involved increased as infection progressed, but never attained more than a limited distribution, even at the clinical stage of disease. The appearance of PrP(TSE) in muscles during the preclinical stage of disease was probably due to the haematogenous/lymphatic spread of infectivity from the gastrointestinal tract to lymphatic tissues associated with muscles, whereas in symptomatic animals, the presence of PrP(TSE) in the nervous system, in neuromuscular junctions and in muscle fibres suggests a centrifugal spread from the central nervous system, as already observed in other TSE models.

Intranasal oxytocin administration promotes emotional contagion and reduces aggression in a mouse model of callousness

ABSTRACT Deficits in empathy, the ability to share an emotion of another individual, constitute a hallmark of several psychopathological conditions, including conduct disorder. The co‐occurrence of excess rates of aggression, general violation of societal norms and callous‐unemotional traits confers specific risk for adult psychopathy. In the present study, we relied on a recently devised experimental model of conduct disorder in mice to test the potential efficacy of intranasal oxytocin administration. Two subgroups of BALB/cJ male mice exhibiting opposite profiles in emotional contagion (i.e. socially transmitted adoption of anothers emotional states) underwent a series of tests mapping onto reactive aggression, information processing, perseverative behaviour, punishment‐related emotional memory, physiological arousal and hormonal stress reactivity, with or without intranasal oxytocin administration (5.0 or 20.0&mgr;g/kg). Collectively, our data indicate that a trait of markedly reduced emotional contagion is associated with a behavioural syndrome of sensorimotor gating deficits, impaired emotional memory, increased aggression and stereotyped behaviours, dysregulations in the circadian rhythms of activity and body temperature and dampened physiological reactivity to external stressors. Moreover, in the absence of changes in oxytocin receptor density in the neural network involved in empathy‐like behaviour, we showed that oxytocin administration normalised emotional contagion, aggression and behavioural stereotypies, thereby ameliorating the phenotype of mice characterised by deficient empathy‐like behaviour. Besides, oxytocin led to a lower, more prolonged neuroendocrine response of the HPA‐axis to stress in all mice. Ultimately, current data support the notion that oxytocin may constitute a valid therapeutic approach in disturbances characterised by abnormal aggression and excess callousness. HIGHLIGHTSCallous‐unemotional traits are defined by low responsiveness to the emotions of others.We tested the efficacy of intranasal oxytocin in a mouse model of conduct disorder.Emotional contagion resistant (EC‐R) mice showed increased aggression.Reduced stress reactivity and punishment‐related memory were associated in EC‐R mice.Oxytocin ameliorated the phenotype of mice with deficient empathy‐like behaviour.

New fluorinated 1,4-bis-(arylaminomethyl)- and 1,4-bis-(arylaminomethylene)benzenes as fluorescent probes for amyloid plaques in Alzheimer's disease and transmissible spongiform encephalopathies

The research into selective ligands of misfolded protein plaques in Alzheimers disease and in transmissible spongiform encephalopathies led to compound 3, based on the Congo Red framework and bearing two trifluoromethoxy groups. Histochemical experiments on human brain tissues showed intense fluorescent staining of fibrillary deposits in both pathologies.

T2-Weighted MRI Signal Alterations in the Early-Clinical Phase of Transmissible Spongiform Encephalopathy in a Scrapie Rodent Model

Background and Purpose: Transmissible spongiform encephalopathy (TSE) diseases are fatal, progressive neurodegenerative disorders affecting both humans and animals. Clinical signs typically appear after years and even decades of silent disease progression. This study was aimed at investigating whether altered brain MRI patterns may precede clinical signs in a TSE rodent model. Methods: In vivo T2-weighted (T2W) MRI examinations (4.7 T) were performed on Golden Syrian hamsters (GSH) intracerebrally, orally, or intraperitoneally (i.p.) infected with the 263K scrapie strain. Histopathological analyses were performed on i.p. infected GSH at the end of one-day or longitudinal MRI sessions. Results: T2W-MRI hyperintensity was detected in the thalamic nuclei of GSH with clinical signs, irrespective of the infection route. Hyperintensity in the thalamus was also observed in pre-clinical animals, between 106 and 121 days post-infection (dpi), while normal T2W intensity was detected in four animals examined between 72 and 96 dpi. Pathological prion protein deposition (but no astrogliosis and only occasionally, weak spongiosis) was detected between 106 and 121 dpi. Conclusions: The altered T2W-MRI pattern detected in the thalamus of asymptomatic i.p. infected GSH provides a useful basis for evaluating the effectiveness of possible therapeutic approaches at early stages of TSE disease.