In vivo imaging of neuroinflammation in Alzheimer's disease
Diverse neurological dementias show neuropathological features, such as deposition of abnormal protein aggregates, as exemplified by accumulation of amyloid beta peptide and tau proteins in Alzheimer's disease. These pathological changes are accompanied by activation of inflammatory microglia and astrocytes, which act on neurons either deleteriously or protectively. Several molecular markers including 18 kDa translocator protein are known to be upregulated in aggressive microglia exerting neurotoxicity, and in vivo visualization of these components potentially contributes to assessments of the disease severity. Meanwhile, biological indicators for other microglial and astrocytic phenotypes are yet to be identified. Inflammatory microgliosis has also been found to have bidirectional mechanistic links to amyloid beta peptide and tau pathologies, and neurodegeneration, supporting the view that modifications of degenerative dementias will be enabled by optimizing immunotherapeutic approaches to neuroinflammation with the aid of imaging modalities targeting specific glial phenotypes.