scholarly journals Neuroinflammation, Microglia, and Cell-Association during Prion Disease

Viruses ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 65 ◽  
Author(s):  
James Carroll ◽  
Bruce Chesebro
Keyword(s):  
Central Nervous System ◽  
Prion Disease ◽  
Host Defense ◽  
Prion Diseases ◽  
Infectious Agent ◽  
Prion Infection ◽  
Cell Association ◽  
Prion Propagation ◽  
The Central Nervous System ◽  
The Brain

Prion disorders are transmissible diseases caused by a proteinaceous infectious agent that can infect the lymphatic and nervous systems. The clinical features of prion diseases can vary, but common hallmarks in the central nervous system (CNS) are deposition of abnormally folded protease-resistant prion protein (PrPres or PrPSc), astrogliosis, microgliosis, and neurodegeneration. Numerous proinflammatory effectors expressed by astrocytes and microglia are increased in the brain during prion infection, with many of them potentially damaging to neurons when chronically upregulated. Microglia are important first responders to foreign agents and damaged cells in the CNS, but these immune-like cells also serve many essential functions in the healthy CNS. Our current understanding is that microglia are beneficial during prion infection and critical to host defense against prion disease. Studies indicate that reduction of the microglial population accelerates disease and increases PrPSc burden in the CNS. Thus, microglia are unlikely to be a foci of prion propagation in the brain. In contrast, neurons and astrocytes are known to be involved in prion replication and spread. Moreover, certain astrocytes, such as A1 reactive astrocytes, have proven neurotoxic in other neurodegenerative diseases, and thus might also influence the progression of prion-associated neurodegeneration.

scholarly journals Microglia Are Critical in Host Defense against Prion Disease

2018 ◽  
Vol 92 (15) ◽  
Author(s):  
James A. Carroll ◽  
Brent Race ◽  
Katie Williams ◽  
James Striebel ◽  
Bruce Chesebro
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Prion Disease ◽  
Host Defense ◽  
Clinical Signs ◽  
Clinical Disease ◽  
Oral Drug ◽  
Early Event ◽  
Prion Infection ◽  
The Central Nervous System

ABSTRACT Microglial cells in the central nervous system play important roles in neurodevelopment and resistance to infection, yet microglia can become neurotoxic under some conditions. An early event during prion infection is the activation of microglia and astrocytes in the brain prior to damage or death of neurons. Previous prion disease studies using two different strategies to manipulate signaling through the microglial receptor CSF-1R reported contrary effects on survival from prion disease. However, in these studies, reductions of microglial numbers and function were variable, thus confounding interpretation of the results. In the present work, we used oral treatment with a potent inhibitor of CSF-1R, PLX5622, to eliminate 78 to 90% of microglia from cortex early during the course of prion infection. Oral drug treatment early after infection with the RML scrapie strain significantly accelerated vacuolation, astrogliosis, and deposition of disease-associated prion protein. Furthermore, drug-treated mice had advanced clinical disease requiring euthanasia 31 days earlier than untreated control mice. Similarly, PLX5622 treatment during the preclinical phase at 80 days postinfection with RML scrapie also accelerated disease and resulted in euthanasia of mice 33 days earlier than infected controls. PLX5622 also accelerated clinical disease after infection with scrapie strains ME7 and 22L. Thus, microglia are critical in host defense during prion disease. The early accumulation of PrPSc in the absence of microglia suggested that microglia may function by clearing PrPSc, resulting in longer survival. IMPORTANCE Microglia contribute to many aspects of health and disease. When activated, microglia can be beneficial by repairing damage in the central nervous system (CNS) or they can turn harmful by becoming neurotoxic. In prion and prionlike diseases, the involvement of microglia in disease is unclear. Previous studies suggest that microglia can either speed up or slow down disease. In this study, we infected mice with prions and depleted microglia from the brains of mice using PLX5622, an effective CSF-1R tyrosine kinase inhibitor. Microglia were markedly reduced in brains, and prion disease was accelerated, so that mice needed to be euthanized 20 to 33 days earlier than infected control mice due to advanced clinical disease. Similar results occurred when mice were treated with PLX5622 at 80 days after infection, which was just prior to the start of clinical signs. Thus, microglia are important for removing prions, and the disease is faster when microglia are depleted.

scholarly journals Distribution of microRNA profiles in pre-clinical and clinical forms of murine and human prion disease

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Lesley Cheng ◽  
Camelia Quek ◽  
Xia Li ◽  
Shayne A. Bellingham ◽  
Laura J. Ellett ◽  
...  
Keyword(s):  
Prion Disease ◽  
Molecular Subtype ◽  
Prion Diseases ◽  
Clinical Stage ◽  
Clinical Samples ◽  
Serum Samples ◽  
Prion Infection ◽  
Clinical Forms ◽  
Therapeutic Development ◽  
The Brain

AbstractPrion diseases are distinguished by long pre-clinical incubation periods during which prions actively propagate in the brain and cause neurodegeneration. In the pre-clinical stage, we hypothesize that upon prion infection, transcriptional changes occur that can lead to early neurodegeneration. A longitudinal analysis of miRNAs in pre-clinical and clinical forms of murine prion disease demonstrated dynamic expression changes during disease progression in the affected thalamus region and serum. Serum samples at each timepoint were collected whereby extracellular vesicles (EVs) were isolated and used to identify blood-based biomarkers reflective of pathology in the brain. Differentially expressed EV miRNAs were validated in human clinical samples from patients with human sporadic Creutzfeldt-Jakob disease (sCJD), with the molecular subtype at codon 129 either methionine-methionine (MM, n = 14) or valine-valine (VV, n = 12) compared to controls (n = 20). EV miRNA biomarkers associated with prion infection predicted sCJD with an AUC of 0.800 (85% sensitivity and 66.7% specificity) in a second independent validation cohort (n = 26) of sCJD and control patients with MM or VV subtype. This study discovered clinically relevant miRNAs that benefit diagnostic development to detect prion-related diseases and therapeutic development to inhibit prion infectivity.

The Neuroimmune Interface in Prion Diseases

Physiology ◽  
2000 ◽  
Vol 15 (5) ◽  
pp. 250-255
Author(s):  
Michael A. Klein ◽  
Adriano Aguzzi
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Immune System ◽  
Prion Disease ◽  
Neurodegenerative Disorders ◽  
Prion Diseases ◽  
The Central Nervous System

Prion diseases are fatal neurodegenerative disorders of animals and humans. Here we address the role of the immune system in the spread of prions from peripheral sites to the central nervous system and its potential relevance to iatrogenic prion disease.

Macrophages in the Brain: Friends or Enemies?

Physiology ◽  
1994 ◽  
Vol 9 (2) ◽  
pp. 80-84 ◽  
Author(s):  
D Piani ◽  
DB Constam ◽  
K Frei ◽  
A Fontana
Keyword(s):  
Central Nervous System ◽  
Host Defense ◽  
The Body ◽  
Defense System ◽  
Tissue Destruction ◽  
Brain Macrophages ◽  
Host Defense System ◽  
The Central Nervous System ◽  
The Brain ◽  
Macrophage Lineage

Cells of the macrophage lineage are ubiquitously distributed in the body, including the central nervous system. They represent an essential host defense system to protect from infections. However, recent evidence indicates that brain macrophages may also be responsible for tissue destruction, including loss of neurons and demyelination.

scholarly journals Prion propagation in mice lacking central nervous system NF-κB signalling

2008 ◽  
Vol 89 (6) ◽  
pp. 1545-1550 ◽  
Author(s):  
C. Julius ◽  
M. Heikenwalder ◽  
P. Schwarz ◽  
A. Marcel ◽  
M. Karin ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Immune Responses ◽  
Published Data ◽  
Histopathological Changes ◽  
Prion Infection ◽  
Prion Propagation ◽  
Proliferation Regulation ◽  
The Impact ◽  
The Brain

Prions induce highly typical histopathological changes including cell death, spongiosis and activation of glia, yet the molecular pathways leading to neurodegeneration remain elusive. Following prion infection, enhanced nuclear factor-κB (NF-κB) activity in the brain parallels the first pathological changes. The NF-κB pathway is essential for proliferation, regulation of apoptosis and immune responses involving induction of inflammation. The IκB kinase (IKK) signalosome is crucial for NF-κB signalling, consisting of the catalytic IKKα/IKKβ subunits and the regulatory IKKγ subunit. This study investigated the impact of NF-κB signalling on prion disease in mouse models with a central nervous system (CNS)-restricted elimination of IKKβ or IKKγ in nearly all neuroectodermal cells, including neurons, astrocytes and oligodendrocytes, and in mice containing a non-phosphorylatable IKKα subunit (IKKα AA/AA). In contrast to previously published data, the observed results showed no evidence supporting the hypothesis that impaired NF-κB signalling in the CNS impacts on prion pathogenesis.

scholarly journals Glycosylation of PrPC Determines Timing of Neuroinvasion and Targeting in the Brain following Transmissible Spongiform Encephalopathy Infection by a Peripheral Route

2010 ◽  
Vol 84 (7) ◽  
pp. 3464-3475 ◽  
Author(s):  
Enrico Cancellotti ◽  
Barry M. Bradford ◽  
Nadia L. Tuzi ◽  
Raymond D. Hickey ◽  
Debbie Brown ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Transmissible Spongiform Encephalopathy ◽  
Disease Onset ◽  
Infectious Agent ◽  
Spongiform Encephalopathy ◽  
Infectious Process ◽  
Key Factor ◽  
The Central Nervous System ◽  
The Brain

ABSTRACT Transmissible spongiform encephalopathy (TSE) infectivity naturally spreads from site of entry in the periphery to the central nervous system where pathological lesions are formed. Several routes and cells within the host have been identified as important for facilitating the infectious process. Expression of the glycoprotein cellular PrP (PrPC) is considered a key factor for replication of infectivity in the central nervous system (CNS) and its transport to the brain, and it has been suggested that the infectious agent propagates from cell to cell via a domino-like effect. However, precisely how this is achieved and what involvement the different glycoforms of PrP have in these processes remain to be determined. To address this issue, we have used our unique models of gene-targeted transgenic mice expressing different glycosylated forms of PrP. Two TSE strains were inoculated intraperitoneally into these mice to assess the contribution of diglycosylated, monoglycosylated, and unglycosylated PrP in spreading of infectivity to the brain. This study demonstrates that glycosylation of host PrP has a profound effect in determining the outcome of disease. Lack of diglycosylated PrP slowed or prevented disease onset after peripheral challenge, suggesting an important role for fully glycosylated PrP in either the replication of the infectious agent in the periphery or its transport to the CNS. Moreover, mice expressing unglycosylated PrP did not develop clinical disease, and mice expressing monoglycosylated PrP showed strikingly different neuropathologic features compared to those expressing diglycosylated PrP. This demonstrates that targeting in the brain following peripheral inoculation is profoundly influenced by the glycosylation status of host PrP.

scholarly journals The microbiota protects from viral-induced neurologic damage through microglia-intrinsic TLR signaling

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
D Garrett Brown ◽  
Raymond Soto ◽  
Soumya Yandamuri ◽  
Colleen Stone ◽  
Laura Dickey ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Oral Administration ◽  
Viral Replication ◽  
Viral Infection ◽  
Host Defense ◽  
Toll Like Receptor ◽  
Tlr Signaling ◽  
The Central Nervous System ◽  
The Brain

Symbiotic microbes impact the function and development of the central nervous system (CNS); however, little is known about the contribution of the microbiota during viral-induced neurologic damage. We identify that commensals aid in host defense following infection with a neurotropic virus through enhancing microglia function. Germfree mice or animals that receive antibiotics are unable to control viral replication within the brain leading to increased paralysis. Microglia derived from germfree or antibiotic-treated animals cannot stimulate viral-specific immunity and microglia depletion leads to worsened demyelination. Oral administration of toll-like receptor (TLR) ligands to virally infected germfree mice limits neurologic damage. Homeostatic activation of microglia is dependent on intrinsic signaling through TLR4, as disruption of TLR4 within microglia, but not the entire CNS (excluding microglia), leads to increased viral-induced clinical disease. This work demonstrates that gut immune-stimulatory products can influence microglia function to prevent CNS damage following viral infection.

scholarly journals Early Generation of New PrPSc on Blood Vessels after Brain Microinjection of Scrapie in Mice

mBio ◽  
2015 ◽  
Vol 6 (5) ◽  
Author(s):  
Bruce Chesebro ◽  
James Striebel ◽  
Alejandra Rangel ◽  
Katie Phillips ◽  
Andrew Hughson ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Basement Membrane ◽  
Neurodegenerative Diseases ◽  
Blood Vessels ◽  
Protein Misfolding ◽  
Interstitial Fluid ◽  
Prion Diseases ◽  
The Central Nervous System ◽  
The Brain

ABSTRACT Aggregation of misfolded host proteins in the central nervous system is believed to be important in the pathogenic process in several neurodegenerative diseases of humans, including prion diseases, Alzheimer's disease, and Parkinson's disease. In these diseases, protein misfolding and aggregation appear to expand through a process of seeded polymerization. Prion diseases occur in both humans and animals and are experimentally transmissible orally or by injection, thus providing a controllable model of other neurodegenerative protein misfolding diseases. In rodents and ruminants, prion disease has a slow course, lasting months to years. Although prion infectivity has been detected in brain tissue at 3 to 4 weeks postinfection (p.i.), the details of early prion replication in the brain are not well understood. Here we studied the localization and quantitation of PrPSc generation in vivo starting at 30 min postmicroinjection of scrapie into the brain. In C57BL mice at 3 days p.i., generation of new PrPSc was detected by immunohistochemistry and immunoblot assays, and at 7 days p.i., new generation was confirmed by real-time quaking-induced conversion assay. The main site of new PrPSc generation was near the outer basement membrane of small and medium blood vessels. The finding and localization of replication at this site so early after injection have not been reported previously. This predominantly perivascular location suggested that structural components of the blood vessel basement membrane or perivascular astrocytes might act as cofactors in the initial generation of PrPSc. The location of PrPSc replication at the basement membrane also implies a role for the brain interstitial fluid drainage in the early infection process. IMPORTANCE Neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, and prion diseases, of humans are characterized by misfolding and aggregation of certain proteins, resulting in the destruction of brain tissue. In these diseases, the damage process spreads progressively within the central nervous system, but only prion diseases are known to be transmissible between individuals. Here we used microinjection of infectious prion protein (PrPSc) into the mouse brain to model early events of iatrogenic prion transmission via surgical instruments or tissue grafts. At 3 and 7 days postinjection, we detected the generation of new PrPSc, mostly on the outer walls of blood vessels near the injection site. This location and very early replication were surprising and unique. Perivascular prion replication suggested the transport of injected PrPSc via brain interstitial fluid to the basement membranes of blood vessels, where interactions with possible cofactors made by astrocytes or endothelia might facilitate the earliest cycles of prion infection.

scholarly journals BAMBI and CHGA in Prion Diseases: Neuropathological Assessment and Potential Role as Disease Biomarkers

Biomolecules ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 706 ◽  
Author(s):  
Óscar López-Pérez ◽  
Marcos Bernal-Martín ◽  
Adelaida Hernaiz ◽  
Franc Llorens ◽  
Marina Betancor ◽  
...  
Keyword(s):  
Prion Diseases ◽  
Enzyme Linked Immunosorbent Assay ◽  
Protein Distribution ◽  
Prion Infection ◽  
Prion Propagation ◽  
Transgenic Murine Model ◽  
Jakob Disease ◽  
The Central Nervous System

Prion diseases affect both animals and humans. Research in the natural animal model of the disease could help in the understanding of neuropathological mechanisms and in the development of biomarkers for human pathologies. For this purpose, we studied the expression of 10 genes involved in prion propagation in vitro in the central nervous system of scrapie-infected sheep. Dysregulated genes (BAMBI and CHGA) were further analysed in a transgenic murine model (Tg338) of scrapie, and their protein distribution was determined using immunohistochemistry and Western blot. Their potential as biomarkers was finally assessed using enzyme-linked immunosorbent assay (ELISA) in cerebrospinal fluid (CSF) of scrapie sheep and Creutzfeldt-Jakob disease (CJD) patients. Protein BAMBI was upregulated in highly affected brain areas and CHGA was overexpressed along the brain in both models. Moreover, BAMBI and CHGA immunostaining scores strongly correlated with spongiosis and microgliosis in mice. Finally, levels of BAMBI were significantly higher in the CSF of clinical sheep and CJD patients. In addition to their potential as biomarkers, our work confirms the role of BAMBI and CHGA in prion neuropathology in vivo, but besides prion replication, they seem to be involved in the characteristic neuroinflammatory response associated to prion infection.

scholarly journals Early Spread of Scrapie from the Gastrointestinal Tract to the Central Nervous System Involves Autonomic Fibers of the Splanchnic and Vagus Nerves

2001 ◽  
Vol 75 (19) ◽  
pp. 9320-9327 ◽  
Author(s):  
Patricia A. McBride ◽  
Walter J. Schulz-Schaeffer ◽  
Maura Donaldson ◽  
Moira Bruce ◽  
H. Diringer ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Central Nervous System ◽  
Nervous System ◽  
Infectious Agent ◽  
Temporal Sequence ◽  
Autonomic Ganglia ◽  
Enteric Ganglia ◽  
The Central Nervous System ◽  
Brain And Spinal Cord ◽  
The Brain

ABSTRACT Although the ultimate target of infection is the central nervous system (CNS), there is evidence that the enteric nervous system (ENS) and the peripheral nervous system (PNS) are involved in the pathogenesis of orally communicated transmissible spongiform encephalopathies. In several peripherally challenged rodent models of scrapie, spread of infectious agent to the brain and spinal cord shows a pattern consistent with propagation along nerves supplying the viscera. We used immunocytochemistry (ICC) and paraffin-embedded tissue (PET) blotting to identify the location and temporal sequence of pathological accumulation of a host protein, PrP, in the CNS, PNS, and ENS of hamsters orally infected with the 263K scrapie strain. Enteric ganglia and components of splanchnic and vagus nerve circuitry were examined along with the brain and spinal cord. Bioassays were carried out with selected PNS constituents. Deposition of pathological PrP detected by ICC was consistent with immunostaining of a partially protease-resistant form of PrP (PrPSc) in PET blots. PrPSc could be observed from approximately one-third of the way through the incubation period in enteric ganglia and autonomic ganglia of splanchnic or vagus circuitry prior to sensory ganglia. PrPSc accumulated, in a defined temporal sequence, in sites that accurately reflected known autonomic and sensory relays. Scrapie agent infectivity was present in the PNS at low or moderate levels. The data suggest that, in this scrapie model, the infectious agent primarily uses synaptically linked autonomic ganglia and efferent fibers of the vagus and splanchnic nerves to invade initial target sites in the brain and spinal cord.

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