The potential association of neuroinflammation with disease progression from the early stages of Alzheimer's disease (AD) has been subject of investigation since the finding that activated microglia and astrocytes are located in close proximity of senile plaques in AD patients. Further than activated microglia and astrocytes, increased levels of proinflammatory cytokines are associated to AD. Microglia serve as immunosurveillance in the central nervous system constantly excavating the tissue for damaged neurons, plaques and infectious agents. In case of infection, microglial cells are known to act rapidly to decrease the inflammation and destroy infectious agents before they damage neuronal tissue. As a result of the presence of beta amyloid plaques and neurofibrillary tangles, microglial cells are activated through a cascade reaction induced by their interaction with fibrillar Ab and respond by over expression of chemokines, prostaglandins (e.g. prostaglandin J2), neurotoxic cytokines (interleukin-6, tumor necrosis factor alpha), reactive oxygen species (e.g. superoxide anion) and nitrogen species, all known to be directly deleterious to the CNS. Even though a wide range of studies indicate a potential link between neuroinflammation and AD, current models of AD failed to address the potential mechanisms by which an inflammatory response could induce AD related neurodegeneration.
The main question to address in this project is to establish the response of Ab on inflammatory factors. In vitro biophysical assays are uniquely placed to obtain mechanistic insight into the etiopathological relation of inflammation with AD. In-detail mechanistic information can be obtained because many biophysical assays are suitable to approach (near-)atomic resolution. The effect of individual inflammatory factors will be assessed in an unequivocal manner, including interleukins, prostaglandins and other cytokines and chemokines.
You will first establish if and how inflammatory conditions can induce Ab to oligomerize and aggregate and to form toxic Ab species. The kinetics of Ab aggregation can be assayed by a variety of techniques which will all provide in-detail information on any deviation of the aggregation pathways. Assays employed will include thioflavin T fluorescence, atomic force microscopy (AFM), A11 immunostaining, and circular dichroism (CD).
The effect of Ab on the RNA expression pattern of specific cytokines by monocytes will be assayed using PCR. The results from this investigation will be further explored using a similar set-up as mentioned above to investigate Ab aggregation.
Once the effects of the different inflammatory factors on the aggregation of Ab have been established, it is important to investigate the cytotoxic response to the Ab species formed. A time resolved assay will be performed in which Ab will be aged in the presence of the various inflammatory factors and at specific time points, aliquots will be collected and co-incubated with the hippocampal neuronal cells. The toxic effect of the different aliquots will be probed by a Cell Titer Blue assay.
Last, it will be interesting in this respect to investigate how the progress of AD can be modulated by administration of nonsteroidal anti-inflammatory drugs (NSAIDs). A similar set-up will be used to investigate the effect of the presence of NSAIDs on cytokine-induced Ab aggregation and toxicity.
This multidisciplinary project can be further extended to include more advanced biological techniques, such as immunostaining, subject to the interest of the student.
Kerensa Broersen, PhD