3,276 research outputs found
Mabbott Group data archive
No full text## Access ## This dataset is held in the Edinburgh DataVault, directly accessible only to authorised University of Edinburgh staff. External users may request access to a copy of the data by contacting the Principal Investigator, Contact Person or Data Manager named on this page. University of Edinburgh users who wish to have direct access should consult the information about retrieving data from the DataVault at: https://www.ed.ac.uk/is/research-support/datavault .Archive of group drive data from the Mabbott Group. This archive includes project data from the following individuals: Alejandra Sanchez (PhD 2018), Anuj Sehgal (PhD 2016), Atshushi Kobayashi (Sabbatical), Barbara Shih, Bridget Glaysher (PhD 2007), Claudine Raymond, Tom Freeman (Biolayout analyses)
Determining the role of mononuclear phagocyte cell subsets in scrapie transmission from the skin
No full textTransmissible spongiform encephalopathies (TSEs), or prion diseases, are fatal
neurodegenerative diseases that affect several species, such as scrapie in sheep or
goats and CJD in humans. In several species, neurological disease is preceded by
TSE agent accumulation in lymphoid tissues prior to neuroinvasion. While oral
transmission is considered the most common route for scrapie, transmission can also
occur through lesions to the skin or mucosa, for example in the mouth or
gastrointestinal tract due to rough feed, or birth associated skin damage. Scrapie has
also been experimentally transmitted through skin scarification in mice. Following
scrapie infection via skin scarification, PrPSc accumulates in the draining lymph node
(LN) before spreading to other organs in the lymphoreticular system. It is not yet
known by what means the scrapie agent is transported from the skin to the draining
LN. Dendritic cells (DCs) in the skin have been found to transport viruses, such as
HIV or Dengue, from the skin, thereby raising the question whether DCs or
Langerhans cells (LCs), located within the epidermis, play a role in the uptake and
transport of the TSE agent from the skin to the draining LN.
CD11c is a cell surface marker traditionally used to identify or isolate DCs from
other cell types. Mice and rats are naturally resistant to Diphtheria toxin (DTX). A
transgenic mouse line was created where the Diphtheria toxin receptor (DTR) was
expressed on CD11c+ cells. The presence of this receptor on CD11c+ cells allowed
for the temporary conditional depletion of CD11c+ cells following a single injection
of DTX. The cells repopulate the tissues within a time frame specific to the tissues
the cells are located in. These mice were used to determine whether the absence of
CD11c+ cells at the time of scrapie infection via the skin had an effect on the early
accumulation of PrPSc within the lymphoid tissues and on disease progression.
Immunohistochemical analysis demonstrated that early PrPSc accumulation in the
draining LNs was delayed following depletion of CD11c+ cells, indicating that their
potential role in the transport of the scrapie agent from the skin. Scrapie incubation
period was not affected by the absence of the CD11c+ cells at the time of infection.
Recent findings show that CD11c is not exclusive to DCs and is also expressed on
macrophage populations. Following DTX-mediated depletion, DCs repopulate the
tissues much faster than CD11c+ macrophages. Scrapie infection was carried out in
the skin in DTX treated mice after DCs had repopulated the tissues but before
macrophage numbers had returned, to determine whether macrophages rather than
DCs played a role in the early accumulation of PrPSc in the draining LNs. No
differences in PrPSc accumulation were observed in mice depleted of macrophages
compared to controls and there was no effect on disease incubation period.
Another transgenic mouse line was used, where DTX expression on langerin+ cells
(LCs and langerin+ DCs in the dermis), allowed for their temporary depletion
through DTX treatment. Following langerin+ cell depletion, increased PrPSc
accumulation was observed in the draining LNs 7 weeks post infection, but did not
affect the incubation period of disease. These results indicate that the absence of LCs
somehow accelerated PrPSc accumulation, and that LCs might play a preventative
role in early stages after infection.Histopathological analysis was used to complement microarray studies aimed to
determine what immune responses were associated with scarification and DTXmediated
depletion of cells within the skin and whether these responses might be
linked to disease transmission.
DCs and LCs in the skin appear to play different roles in the early stages following
scrapie infection via the skin, but the lack of effect on incubation period does not rule
out the involvement of other cell types or cell-free mechanisms of scrapie agent
spread from the skin
The impact of innate immune modifications in prion disease pathogenesis
No full textPrion diseases are a group of infectious, chronic, fatal, and progressive neurodegenerative diseases with no treatments or cures to date. During disease, the central nervous system (CNS) presents extensive accumulation of misfolded prions, reactive gliosis, neuronal spongiform vacuolation and dementia. The mononuclear phagocytes (MNPs) comprise a fundamental component of the innate immune system and are considered to mediate the sequestration and destruction of infectious prions. Therefore, the aims of this thesis were to interrogate prion disease pathogenesis and susceptibility after reducing the abundance of MNPs, restricting their pro-inflammatory phenotype, and modifying their activation through innate immune stimulation.
Data in this thesis show that peripheral stimulation of mice with an intraperitoneal (IP) injection of bacterial lipopolysaccharide (LPS) 3 hours prior to a subsequent IP injection with a limiting dose of prions significantly enhanced prion disease susceptibility. Further analysis showed that within 3 hours of LPS treatment the number of CD11b+MHCIIlowCD102high large peritoneal macrophages and CD11b+MHCIIhighCD102low small peritoneal macrophages were significantly reduced compared to mice treated with saline. This revealed that peripheral LPS stimulation had induced the disappearance of macrophages in the peritoneal cavity. Together these data suggest that the increased susceptibility to IP prion infection in the LPS- treated mice was due to the reduced abundance of MNPs in the peritoneal cavity which increased the ability of the prions to infect the CNS.
In the brain, a single IP injection with LPS (1x LPS) had been shown to induce microglial innate immune training, whereas four consecutive doses (4x LPS) every 24 hours induced microglial innate immune tolerance. The innate immune tolerised phenotype in the microglia had been previously demonstrated to reduce the amyloidosis in an Alzheimer’s like mouse model, and this response was observed 6 months after LPS stimulation. To test whether innate immune tolerance in microglia might similarly impede the development of CNS prion disease, groups of mice received an intracerebral (IC) injection of prions then 35 days later stimulated with 4x LPS by the IP route. Data from this study showed that neither microglial innate immune training (1x LPS) or tolerance (4x LPS) significantly affected the clinical presentation of prion disease nor the accumulation of misfolded prions in the CNS. This suggests that LPS mediated innate immune tolerance in the microglia does not influence prion mediated neuropathology in mice, despite their beneficial effects previously seen in an Alzheimer’s like mouse model.
MNPs require constant signalling through their Colony Stimulating Factor 1 Receptor (CSF1R) for their survival and maintenance. Previous data had shown that a transgenic mouse containing a Csf1r tyrosine kinase dead mutation (Csf1rE631K/+) had a significantly reduced number of microglia in the brain. In addition, bone marrow cells collected from these mice were unresponsive to stimulation with the cytokine CSF1 which suggests an impairment in CSF1R signalling. To test whether an impairment in CSF1R signalling restricts microglial expansion in CNS prion disease or modifies disease pathogenesis, a group of Csf1rE631K/+ mice received an IC injection with prions and the effects on CNS prion disease determined. Whilst the prion infected Csf1rE631K/+ mice presented a significantly lower abundance of microglia compared to those found in prion infected wildtype mice, a significant increase in the number of microglia was observed in both Csf1rE631K/+ mice and wildtype mice during CNS prion disease. However, it was found that the rate of microglial expansion across disease was not significantly affected in the Csf1rE631K/+ mice with an impairment in CSF1R signalling. Likewise, there were no significant changes in the development or severity of prion mediated neuropathology. This suggests that although an impairment in CSF1R signalling in the Csf1rE631K/+ mice restricted the overall density of the microglia in the brain, this did not impact on their rate of expansion, nor CNS prion disease pathogenesis. These data infer that microglial expansion does not likely require CSF1R signalling in prion disease.
Together data from this thesis suggest a protective role of macrophages in the peritoneal cavity by constraining peripheral prion infection. However, modification of the microglial phenotype using innate immune tolerance or reducing their abundance using the Csf1rE631K/+ mutation provided limited effects on the development and pathogenesis of CNS prion disease. Further elucidation into the factors that drive MNP activation and interrogating their functional roles in the development and susceptibility to prion disease may uncover novel interventions to ameliorating CNS pathogenesis
Prion pathogenesis is unaltered in a mouse strain with a permeable blood-brain barrier
No full textTransmissible spongiform encephalopathies (TSEs) are caused by the prion, which consists essentially of PrPSc, an aggregated, conformationally modified form of the cellular prion protein (PrPC). Although TSEs can be experimentally transmitted by intracerebral inoculation, most instances of infection in the field occur through extracerebral routes. The epidemics of kuru and variant Creutzfeldt-Jakob disease were caused by dietary exposure to prions, and parenteral administration of prion-contaminated hormones has caused hundreds of iatrogenic TSEs. In all these instances, the development of postexposure prophylaxis relies on understanding of how prions propagate from the site of entry to the brain. While much evidence points to lymphoreticular invasion followed by retrograde transfer through peripheral nerves, prions are present in the blood and may conceivably cross the blood-brain barrier directly. Here we have addressed the role of the blood-brain barrier (BBB) in prion disease propagation using Pdgfbret/ret mice which possess a highly permeable BBB. We found that Pdgfbret/ret mice have a similar prion disease incubation time as their littermate controls regardless of the route of prion transmission. These surprising results indicate that BBB permeability is irrelevant to the initiation of prion disease, even when prions are administered parenterally
Facing the Future: the Changing Shape of Academic Skills Support at Bournemouth University
No full textThis paper explores the potential impact of changes to higher education in England on student expectations, engagement, lifestyles and diversity, and outlines implications for the development of digital literacy within academic skills support at Bournemouth University (BU). We will investigate how tackling resource constraints with organisational change can also enable efficient, centralised provision of support materials that utilise networks to overcome the risk of fragmented support for digital literacy. We will also look at how changing delivery modes for support can accommodate changing student lifestyles whilst tackling a weakness of centralised support for digital literacy: that it can become detached from the student’s subject-focused academic practice. Finally we will explore how involving students in developing support can help us to face changes to student expectations and engagement whilst ensuring that materials are authentic and speak to learners in their own voice
Prion diseases disrupt glutamate/glutamine metabolism in skeletal muscle
No full textIn prion diseases (PrDs), aggregates of misfolded prion protein (PrP) accumulate not only in the brain but also in extraneural organs. This raises the question whether prion-specific pathologies arise also extraneurally. Here we sequenced mRNA transcripts in skeletal muscle, spleen and blood of prion-inoculated mice at eight timepoints during disease progression. We detected gene-expression changes in all three organs, with skeletal muscle showing the most consistent alterations. The glutamate-ammonia ligase (GLUL) gene exhibited uniform upregulation in skeletal muscles of mice infected with three distinct scrapie prion strains (RML, ME7, and 22L) and in victims of human sporadic Creutzfeldt-Jakob disease. GLUL dysregulation was accompanied by changes in glutamate/glutamine metabolism, leading to reduced glutamate levels in skeletal muscle. None of these changes were observed in skeletal muscle of humans with amyotrophic lateral sclerosis, Alzheimer’s disease, or dementia with Lewy bodies, suggesting that they are specific to prion diseases. These findings reveal an unexpected metabolic dimension of prion infections and point to a potential role for GLUL dysregulation in the glutamate/glutamine metabolism in prion-affected skeletal muscle
Distinct translatome changes in specific neural populations precede electroencephalographic changes in prion-infected mice
No full textSelective vulnerability is an enigmatic feature of neurodegenerative diseases (NDs), whereby a widely expressed protein causes lesions in specific cell types and brain regions. Using the RiboTag method in mice, translational responses of five neural subtypes to acquired prion disease (PrD) were measured. Pre-onset and disease onset timepoints were chosen based on longitudinal electroencephalography (EEG) that revealed a gradual increase in theta power between 10- and 18-weeks after prion injection, resembling a clinical feature of human PrD. At disease onset, marked by significantly increased theta power and histopathological lesions, mice had pronounced translatome changes in all five cell types despite appearing normal. Remarkably, at a pre-onset stage, prior to EEG and neuropathological changes, we found that 1) translatomes of astrocytes indicated reduced synthesis of ribosomal and mitochondrial components, 2) glutamatergic neurons showed increased expression of cytoskeletal genes, and 3) GABAergic neurons revealed reduced expression of circadian rhythm genes. These data demonstrate that early translatome responses to neurodegeneration emerge prior to conventional markers of disease and are cell type-specific. Therapeutic strategies may need to target multiple pathways in specific populations of cells, early in disease
Skin-derived dendritic cells acquire and degrade the scrapie agent following in vitro exposure
No full textThe accumulation of the scrapie agent in lymphoid tissues following inoculation via the skin is critical for efficient neuroinvasion, but how the agent is initially transported from the skin to the draining lymph node is not known. Langerhans cells (LCs) are specialized antigen-presenting cells that continually sample their microenvironment within the epidermis and transport captured antigens to draining lymph nodes. We considered LCs probable candidates to acquire and transport the scrapie agent after inoculation via the skin. XS106 cells are dendritic cells (DCs) isolated from mouse epidermis with characteristics of mature LC cells. To investigate the potential interaction of LCs with the scrapie agent XS106 cells were exposed to the scrapie agent in vitro. We show that XS106 cells rapidly acquire the scrapie agent following in vitro exposure. In addition, XS106 cells partially degrade the scrapie agent following extended cultivation. These data suggest that LCs might acquire and degrade the scrapie agent after inoculation via the skin, but data from additional experiments demonstrate that this ability could be lost in the presence of lipopolysaccharide or other immunostimulatory molecules. Our studies also imply that LCs would not undergo maturation following uptake of the scrapie agent in the skin, as the expression of surface antigens associated with LC maturation were unaltered following exposure. In conclusion, although LCs or DCs have the potential to acquire the scrapie agent within the epidermis our data suggest it is unlikely that they become activated and stimulated to transport the agent to the draining lymph node
Genome-wide transcriptomics identifies an early preclinical signature of prion infection
No full textThe clinical course of prion diseases is accurately predictable despite long latency periods, suggesting that prion pathogenesis is driven by precisely timed molecular events. We constructed a searchable genome-wide atlas of mRNA abundance and splicing alterations during the course of disease in prion-inoculated mice. Prion infection induced PrP-dependent transient changes in mRNA abundance and processing already at eight weeks post inoculation, well ahead of any neuropathological and clinical signs. In contrast, microglia-enriched genes displayed an increase simultaneous with the appearance of clinical signs, whereas neuronal-enriched transcripts remained unchanged until the very terminal stage of disease. This suggests that glial pathophysiology, rather than neuronal demise, could be the final driver of disease. The administration of young plasma attenuated the occurrence of early mRNA abundance alterations and delayed signs in the terminal phase of the disease. The early onset of prion-induced molecular changes might thus point to novel biomarkers and potential interventional targets
Evidence that bank vole PrP is a universal acceptor for prions.
No full textBank voles are uniquely susceptible to a wide range of prion strains isolated from many different species. To determine if this enhanced susceptibility to interspecies prion transmission is encoded within the sequence of the bank vole prion protein (BVPrP), we inoculated Tg(M109) and Tg(I109) mice, which express BVPrP containing either methionine or isoleucine at polymorphic codon 109, with 16 prion isolates from 8 different species: humans, cattle, elk, sheep, guinea pigs, hamsters, mice, and meadow voles. Efficient disease transmission was observed in both Tg(M109) and Tg(I109) mice. For instance, inoculation of the most common human prion strain, sporadic Creutzfeldt-Jakob disease (sCJD) subtype MM1, into Tg(M109) mice gave incubation periods of ∼200 days that were shortened slightly on second passage. Chronic wasting disease prions exhibited an incubation time of ∼250 days, which shortened to ∼150 days upon second passage in Tg(M109) mice. Unexpectedly, bovine spongiform encephalopathy and variant CJD prions caused rapid neurological dysfunction in Tg(M109) mice upon second passage, with incubation periods of 64 and 40 days, respectively. Despite the rapid incubation periods, other strain-specified properties of many prion isolates--including the size of proteinase K-resistant PrPSc, the pattern of cerebral PrPSc deposition, and the conformational stability--were remarkably conserved upon serial passage in Tg(M109) mice. Our results demonstrate that expression of BVPrP is sufficient to engender enhanced susceptibility to a diverse range of prion isolates, suggesting that BVPrP may be a universal acceptor for prions
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