Intrathecal amyloid-beta oligomer administration increases tau phosphorylation in the medial temporal lobe in the African green monkey: A nonhuman primate model of Alzheimer's disease

Aims An obstacle to developing new treatment strategies for Alzheimer's disease (AD) has been the inadequate translation of findings in current AD transgenic rodent models to the prediction of clinical outcomes. By contrast, nonhuman primates (NHPs) share a close neurobiology with humans in virtually all aspects relevant to developing a translational AD model. The present investigation used African green monkeys (AGMs) to refine an inducible NHP model of AD based on the administration of amyloid-beta oligomers (A beta Os), a key upstream initiator of AD pathology. Methods A beta Os or vehicle were repeatedly delivered over 4 weeks to age-matched young adult AGMs by intracerebroventricular (ICV) or intrathecal (IT) injections. Induction of AD-like pathology was assessed in subregions of the medial temporal lobe (MTL) by quantitative immunohistochemistry (IHC) using the AT8 antibody to detect hyperphosphorylated tau. Hippocampal volume was measured by magnetic resonance imaging (MRI) scans prior to, and after, intrathecal injections. Results IT administration of A beta Os in young adult AGMs revealed an elevation of tau phosphorylation in the MTL cortical memory circuit compared with controls. The largest increases were detected in the entorhinal cortex that persisted for at least 12 weeks after dosing. MRI scans showed a reduction in hippocampal volume following A beta O injections. Conclusions Repeated IT delivery of A beta Os in young adult AGMs led to an accelerated AD-like neuropathology in MTL, similar to human AD, supporting the value of this translational model to de-risk the clinical trial of diagnostic and therapeutic strategies.

Automated summary

The use of nonhuman primates as a model for Alzheimer's disease can help to better understand the pathology of the disease.