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ApoE immunoreactivity and microglial cells in Alzheimer's disease brain
T Uchihara1, C Duyckaerts, Y He
1Laboratoire de Neuropathologie, Université Pierre et Marie Curie, INSERM U360, Hôpital de la Salpêtrière, Paris, France.
Abstract:
The spatial relationship of apolipoprotein E (apoE)-like immunoreactivity (IR) to amyloid beta-peptide (A beta), astrocytes and microglial cells in the brain of Alzheimer's disease was studied by double immunolabelling. Diffuse apoE-like IR was seen in A beta diffuse deposits, and markedly increased in the core of classic senile plaques. Microglial cells, sometimes immunoreactive for apoE, were frequent in areas of apoE-like IR, where they often grouped into clusters in the core of apoE-labelled senile plaques. Although astrocytic processes were seen within these senile plaques, the cell bodies were always at a distance from the core. None of these astrocytes expressed apoE-like IR. Microglial cells, some of them immunoreactive for apoE, were seen in the center of apoE-labelled senile plaques. These data suggest that microglial cells play a more significant role than astrocytes in apoE deposition in senile plaques of Alzheimer disease.
Insights
Microglia, not astrocytes, are significantly involved in apolipoprotein E deposition within senile plaques in Alzheimer's disease brains. This finding highlights the crucial role of microglial cells in the pathology of Alzheimer's disease.
Area of Science:
- Neuroscience
- Pathology
- Immunohistochemistry
Background:
- Alzheimer's disease (AD) is characterized by amyloid beta-peptide (A beta) plaques and neuroinflammation.
- Apolipoprotein E (apoE) is implicated in AD pathogenesis, but its cellular localization within plaques is debated.
Purpose of the Study:
- To investigate the spatial relationship between apoE-like immunoreactivity (IR) and key cellular components (A beta, astrocytes, microglia) in Alzheimer's disease brain tissue.
- To elucidate the specific roles of astrocytes and microglial cells in apoE deposition within senile plaques.
Main Methods:
- Double immunolabelling techniques were employed to visualize apoE-like IR, A beta deposits, astrocytes, and microglial cells simultaneously.
- Microscopic analysis focused on the co-localization and distribution of these markers within senile plaques.
Main Results:
- Diffuse apoE-like IR was observed in A beta deposits and concentrated in the core of classic senile plaques.
- Microglial cells, some expressing apoE-like IR, were frequently found clustered within the core of apoE-labelled senile plaques.
- Astrocytic cell bodies were located away from plaque cores and did not exhibit apoE-like IR, though their processes were present within plaques.
Conclusions:
- Microglial cells, rather than astrocytes, appear to be the primary contributors to apoE deposition in senile plaques in Alzheimer's disease.
- These findings underscore the significant role of microglial cells in the neuropathological processes of Alzheimer's disease, particularly in apoE deposition.