Neocortical and hippocampal TREM2 protein levels during the progression of Alzheimer’s disease

Publication date: Available online 9 March 2017
Source:Neurobiology of Aging
Author(s): Sylvia E. Perez, Muhammad Nadeem, Bin He, Jennifer C. Miguel, Michael H. Malek-Ahmadi, Kewei Chen, Elliott J. Mufson
Heterozygous TREM2 mutations are an Alzheimer's disease (AD) risk factor. Non-mutated TREM2 dysregulation occurs in AD brain. Whether TREM2 is altered in prodromal AD remains unknown. Western blotting was used to determine levels of TREM2 (∼ 25 kDa) and Iba1 in the frontal cortex and TREM2 in the hippocampus from people who died with an ante-mortem clinical diagnosis of non- and mild-cognitive impairment, mild/moderate AD (mAD) and severe AD (sAD). Immunohistochemistry defined the relationship between amyloid and Iba1 profiles. PCR analysis revealed that all subjects did not carry the most common R47H TREM2 variant. TREM2 was significantly upregulated in sAD frontal cortex, but stable in hippocampus. Frontal TREM2 mRNA and protein level patterns were similar, but not significantly different. Iba1 immunopositive microglia counts increased significantly in frontal cortex containing plaques in sAD. TREM2 and Iba1 levels were not associated with plaques, tangles, neuropathological criteria or cognitive performance. Frontal cortex TREM2 upregulation is a late event and may not play a major role early in the pathogenesis of the disease.



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