Casati M, et al. - Researchers explored the expression of triggering receptor expressed on myeloid cells 2 (TREM2) in peripheral blood mononuclear cells in patients with either Alzheimer's disease (AD) or mild cognitive impairment (MCI). During this study, the protective role of TREM2 in the pre-clinical stage of AD was affirmed. It was deduced that the upregulation of TREM2 in MCI-AD could serve as a mechanism to counteract the activation of the neuroinflammatory processes. Furthermore, TREM2 and apolipoprotein E (ApoE ε4) appeared to interact synergistically in the pre-clinical stage of AD. Thus, TREM2 could prove to be beneficial as an early peripheral biomarker for the development of AD.

Methods

• In peripheral blood mononuclear cells, experts gauged the TREM2 expression from healthy subjects (CT) and from patients with either AD or MCI.
• Re-analysis was conducted of the MCI patients at a 2-year follow-up to evaluate their progression to AD (MCI-AD) or lack thereof (MCI-MCI).

Results

• TREM2 gene expression was higher in AD compared to CT patients, however, it was highest in MCI.
• At recruitment, higher TREM2 levels were reported in MCI-AD than in MCI-MCI, and in MCI-AD was higher initially than at follow-up.
• As per the results, TREM2 illustrated a moderate degree of sensitivity and specificity for detecting MCI-AD in all MCI patients.
• Furthermore, higher TREM2 levels were demonstrated in allele ε4 of ApoE ε4 carriers than non-carriers in MCI and especially in MCI-AD.