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Killing of prion-damaged neurones by microglia
1Department of Veterinary Pathology, University of Glasgow Veterinary School, Bearsden Road, Glasgow G61 1QH, UK.
Abstract:
The loss of neurones that occurs in the transmissible spongiform encephalopathies, or prion diseases, can be reproduced in vitro by incubating neuronal cultures with either peptides derived from the prion protein or with partially purified prion preparations. In the present studies, the extent of neuronal loss on exposure to these prions or prion peptides was increased by the addition of microglia, a process that was dependent upon the number of microglia added, the concentration of prions/peptides present and the degree of fibrillarity of the prion peptides. Microglia also killed scrapie-infected neuroblastoma cells expressing infectious PrP(SC). Microglia secreted low amounts of interleukin (IL)-6 when incubated with peptides alone but up to 10 times as much IL-6 when incubated with peptide-treated neurones, suggesting that microglia recognise peptide-induced changes in neurones.
Insights
Microglia exacerbate neuronal loss in prion diseases by recognizing prion peptides and enhancing neurotoxicity. This interaction, involving interleukin-6 secretion, highlights microglia
Area of Science:
- Neuroscience
- Immunology
- Prion Biology
Background:
- Transmissible spongiform encephalopathies (prion diseases) involve progressive neuronal loss.
- In vitro models using prion peptides or preparations can replicate this neuronal loss.
- The role of microglia, the brain's immune cells, in prion-induced neurodegeneration is under investigation.
Purpose of the Study:
- To investigate the effect of microglia on prion-induced neuronal loss in vitro.
- To determine the factors influencing microglia-mediated neurotoxicity in prion disease models.
- To explore microglia's recognition of prion peptides and their response.
Main Methods:
- Incubation of neuronal cultures with prion peptides or preparations.
- Addition of microglia to neuronal cultures at varying concentrations.
- Assessment of neuronal loss and measurement of interleukin-6 (IL-6) secretion.
- Co-incubation of microglia with scrapie-infected neuroblastoma cells.
Main Results:
- Microglia significantly increased neuronal loss induced by prion peptides/preparations.
- This enhancement was dose-dependent on microglia number, prion concentration, and peptide fibrillarity.
- Microglia also induced cell death in scrapie-infected neuroblastoma cells.
- IL-6 secretion by microglia increased substantially when co-cultured with peptide-treated neurons.
Conclusions:
- Microglia play a critical role in amplifying prion-induced neurodegeneration.
- Microglia appear to recognize prion-induced alterations in neurons, triggering a pro-inflammatory response.
- These findings suggest microglia are key mediators in the pathogenesis of prion diseases.