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Morphogenesis of amyloid plaques in mice with Creutzfeldt-Jakob disease
Abstract:
Amyloid plaques were experimentally produced in the brains of mice inoculated with human Creutzfeldt-Jakob disease (CJD) brain homogenate. Light-microscopically, these plaques were mostly round and oval and were surrounded by macrophages and astrocytes. Ultramicroscopically, amyloid plaques were present in the cytoplasm of macrophages or were surrounded by these cells. The macrophages had numerous Golgi apparatuses, endoplasmic reticula (ER), ribosomes, polysomes, and lysosomes with inoculated materials or degenerating products. The bundles of amyloid fibrils were intermingled with the cytoplasm of macrophages, and sometimes limiting membranes were absent. Some bundles of amyloid fibrils projected from the Golgi apparatuses or rough ER and were partly exposed to the extracellular spaces, but there were no amyloid fibrils in the lysosomes. These findings confirmed that amyloid fibrils in the brains of CJD-infected mice were produced by macrophages.
Insights
Researchers found that macrophages produce amyloid fibrils in the brains of mice infected with Creutzfeldt-Jakob disease (CJD). This study sheds light on the cellular mechanisms behind amyloid plaque formation in prion diseases.
Area of Science:
- Neuroscience
- Immunology
- Pathology
Background:
- Amyloid plaques are a hallmark of neurodegenerative diseases.
- The cellular origin of amyloid fibrils in prion diseases like Creutzfeldt-Jakob disease (CJD) remains incompletely understood.
- Previous studies have implicated various cell types in amyloid formation.
Purpose of the Study:
- To investigate the cellular source of amyloid fibril production in the brains of mice experimentally infected with human CJD.
- To elucidate the ultrastructural mechanisms by which macrophages interact with and potentially produce amyloid fibrils.
Main Methods:
- Experimental inoculation of mice with human CJD brain homogenate.
- Light and ultramicroscopic examination of brain tissue to identify amyloid plaques and associated cells.
- Detailed ultrastructural analysis of macrophages within amyloid plaque areas.
Main Results:
- Amyloid plaques were observed in CJD-infected mouse brains, surrounded by macrophages and astrocytes.
- Ultramicroscopically, amyloid fibrils were found within the cytoplasm of macrophages and in extracellular spaces adjacent to them.
- Macrophages exhibited active cellular machinery (Golgi apparatus, ER, ribosomes) and contained inoculated material, suggesting a role in amyloid synthesis.
- Amyloid fibrils were seen projecting from the Golgi apparatus and rough ER of macrophages.
Conclusions:
- Macrophages are confirmed as the producers of amyloid fibrils in the brains of CJD-infected mice.
- This study provides ultrastructural evidence for macrophage-mediated amyloidogenesis in prion disease.
- Understanding this mechanism may offer new therapeutic targets for CJD and related amyloidopathies.