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Monocyte recruitment into the scrapie-affected brain
A E Williams1, S Ryder, W F Blakemore
1Institute for Animal Health, BBSRC and MRC Neuropathogenesis Unit, Edinburgh, UK.
Abstract:
The recruitment of monocytes into the scrapie-affected brain was investigated in female mice reconstituted with male bone marrow, using a Y-chromosome-specific probe and F4/80 immunocytochemistry. Recruitment of monocytes could be demonstrated in six out of eight animals and the number of recruited cells correlated with the severity of vacuolation in most, but not all, animals. The proportion of microglia derived from recruited monocytes varied between individual animals, did not correlate with the increase in cellularity (glia) in affected areas of brain and did not affect the length of incubation period. Thus, it is unlikely that the recruitment of monocytes is a pivotal event in the development of early pathological changes in scrapie. The morphology of recruited cells in scrapie lesions, as revealed by F4/80 immunoreactivity, was indistinguishable from that of activated resident microglia.
Insights
Monocyte recruitment into the brain during scrapie infection was studied. Results suggest that while monocytes enter the brain, their recruitment is unlikely a pivotal event in early scrapie pathology development.
Area of Science:
- Neuroscience
- Immunology
- Prion Disease Research
Background:
- Scrapie is a fatal neurodegenerative disease caused by prions.
- The role of immune cells, particularly monocytes, in prion disease pathogenesis is not fully understood.
- Microglia are the resident immune cells of the brain and play a role in neuroinflammation.
Purpose of the Study:
- To investigate the recruitment of monocytes into the brain during scrapie infection.
- To determine if monocyte recruitment is a critical factor in the early stages of scrapie pathology.
Main Methods:
- Utilized female mice reconstituted with male bone marrow.
- Employed Y-chromosome-specific probes to track donor-derived cells.
- Used F4/80 immunocytochemistry to identify and characterize myeloid cells, including microglia.
Main Results:
- Monocyte recruitment was observed in 6 out of 8 scrapie-affected mice.
- The number of recruited monocytes generally correlated with vacuolation severity.
- The proportion of microglia derived from recruited monocytes varied and did not correlate with overall cellularity or incubation period.
- Recruited cells exhibited morphology similar to activated resident microglia.
Conclusions:
- Monocyte recruitment into the scrapie-affected brain occurs but is unlikely a pivotal event in early pathological changes.
- The contribution of recruited monocytes to neuroinflammation and disease progression in scrapie appears limited.
- Activated resident microglia, rather than newly recruited monocytes, may be the primary mediators of early pathology.