Related Experiment Videos
Microglial cell activation in aging and Alzheimer disease: partial linkage with neurofibrillary tangle burden in the
1Department of Pathology, University of Texas Medical Branch, Galveston 77550, USA.
Abstract:
Microglial cells are the main component of the brain's resident immune system and are activated in Alzheimer disease (AD). We quantified the density of activated microglial cells (AMG) in 8 sectors of human hippocampus to determine if their density is correlated with senile plaque (SP) and neurofibrillary tangle (NFT) formation. Ferritin-stained microglia, Bielschowsky-stained neuritic plaques, and perikarya containing NFTs were counted in 8 young adults, 9 nondemented elderly adults, and 9 demented patients with AD. Microglial cell activation was moderately higher in elderly nondemented subjects. In AD there was a more striking activation in all sectors of the hippocampus. Most AMGs were distributed diffusely in neuropil and were not delimited to SPs or NFTs. Senile plaque counts were not linked with AMG counts within any sector. Neurofibrillary tangle counts were correlated significantly with AMG counts within one sector, the subiculum. When variations within and between sectors were factored out statistically, the burden of AMGs was correlated significantly with the burden of NFTs (r = 0.34; p < 0.005), but not SPs. Neuropathologic changes at the origin of the perforant pathway were correlated significantly with orthograde microglial cell activation in the termination field. These observations show that correlations between microglial cell activation and pathologic features of AD are only rarely significant. When significant linkage was present, it involved NFTs and not SPs, and depended on which sector of hippocampus was examined.
Insights
Activated microglial cells (AMGs) in Alzheimer disease (AD) hippocampus showed limited correlation with pathology. While AMG burden correlated with neurofibrillary tangles (NFTs), it did not correlate with senile plaques (SPs).
Area of Science:
- Neuroscience
- Immunology
- Neuropathology
Background:
- Microglial cells are key immune cells in the brain, activated in Alzheimer disease (AD).
- Understanding microglial activation patterns is crucial for AD research.
Purpose of the Study:
- To quantify activated microglial cell (AMG) density in human hippocampus sectors.
- To determine correlations between AMG density and senile plaque (SP) and neurofibrillary tangle (NFT) formation in AD.
Main Methods:
- Ferritin-stained microglia, Bielschowsky-stained plaques, and NFT-containing perikarya were counted in 8 hippocampal sectors.
- Subjects included young adults, non-demented elderly, and demented AD patients.
Main Results:
- Microglial activation was higher in non-demented elderly and markedly increased in AD patients across all hippocampal sectors.
- AMG density showed no significant correlation with SP counts in any sector.
- AMG density was significantly correlated with NFT counts in the subiculum and overall (r = 0.34; p < 0.005).
Conclusions:
- Correlations between microglial activation and AD pathology are infrequent and sector-dependent.
- When significant, the association involves NFTs, not SPs, suggesting a specific relationship in certain brain regions.