Glial cells and neuronal function in Alzheimer’s disease
In this thesis, we investigated the impact of Alzheimer’s disease on neuronal function and glial cells. Hereto we used various models, i.e. the APPswePS1dE9 AD mouse model, human post-mortem brain material, and a microglia-like cell model. In a review we focused on the role of reactive astrocytes in the AD mouse model, indicating that reactive astrocytes can be a promising treatment target in AD. Using the same mouse model, we investigated changes in neuronal function at various ages. We concluded that aging has a more prominent effect on the measurements than the increased presence of amyloid. In a first experiment, to investigate the potential role of microglia in AD, we used a microglia-like model to examine the effect of Aβ1-42 oligomers on transcriptomic changes. Interestingly, we observed a distinct upregulation of metallothionein subtypes in the Aβ1-42 oligomer stimulated cells. The upregulation of metallothioneins could have a neuroprotective function against the oxidative stress and neuroinflammation involved in AD, indicating that the acute activation by Aβ1-42 oligomers could induce a protective response. We characterized the Aβ plaque burden and morphology in cortical brain slices of AD patients and non-demented control with amyloid plaques. Even though the last group has overall less Aβ plaques, relatively more dense-core plaques were observed. We found no differences in the total number of microglia or morphology between the groups. Further characterization of plaque-associated microglia suggested a reduced phagocytic activity by microglia surrounding dense-core plaques in NDC+-cases. No difference in synaptic density between AD- and NDC+-cases near dense-core or diffuse plaques was detected.