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Microglia and the development of spongiform change in Creutzfeldt-Jakob disease
U v Eitzen1, R Egensperger, S Kösel
1Institute of Neuropathology, Reference Center for Neurodegenerative Disorders, Ludwig-Maximilians-University, Munich, Germany.
Abstract:
Recent in vitro experiments suggest that neurotoxicity of the prion protein is dependent on the presence of microglia. We have studied 11 cases of Creutzfeldt-Jakob disease (CJD) using immunocytochemistry in combination with computerized image analysis to clarify the relationship between spongiform change and microglial activation. MHC class II-positive microglia were almost exclusively confined to cortical gray matter where the neuropil area occupied by these cells exceeded that of controls more than 350-fold. In cortical regions with a bimodal distribution of spongiform degeneration, the presence of class II-positive microglia correlated well with the presence of vacuolation in layer V, but significantly less with spongiform change in layers II and III. In areas where spongiform degeneration affected the entire depth of the cortex, activated microglia were predominantly located in the inner one-half of the cortex or were evenly distributed throughout all cortical laminae. Here, microglia exhibited atypical, tortuous cell processes and occasionally intracytoplasmic vacuoles, suggesting that microglia themselves may become a disease target. Taken together, our results provide indirect evidence against an early causative involvement of microglia in the development of spongiform change. At later stages, however, diseased microglia could produce harmful factors which mediate both astrogliosis and neuronal injury.
Insights
Microglia activation in Creutzfeldt-Jakob disease (CJD) is linked to spongiform changes, but evidence suggests they are not early causal agents. Diseased microglia may contribute to neuronal injury and astrogliosis in later stages.
Area of Science:
- Neuroscience
- Immunology
- Pathology
Background:
- In vitro studies suggest prion protein neurotoxicity depends on microglia presence.
- Creutzfeldt-Jakob disease (CJD) is a fatal neurodegenerative disorder characterized by prion protein accumulation.
- Microglia are the primary immune cells of the central nervous system.
Observation:
- Studied 11 CJD cases using immunocytochemistry and computerized image analysis.
- MHC class II-positive microglia were significantly increased (over 350-fold) in cortical gray matter of CJD patients.
- Microglial distribution and morphology varied with spongiform degeneration patterns across cortical layers.
Findings:
- Microglial activation correlated with spongiform change in layer V but less so in layers II/III.
- In widespread spongiform degeneration, activated microglia showed atypical morphology and intracytoplasmic vacuoles, suggesting they may be disease targets.
- Results provide indirect evidence against early microglial involvement in spongiform change initiation.
Implications:
- Microglia are not likely early causative agents in CJD spongiform change.
- Later-stage diseased microglia may produce factors mediating astrogliosis and neuronal injury.
- Understanding microglial roles in CJD pathogenesis is crucial for developing therapeutic strategies.