Casati M, et al. - Researchers here analyzed TREM2 expression in peripheral blood mononuclear cells from healthy subjects (CT) and from patients with either Alzheimer's disease (AD) or mild cognitive impairment (MCI) to investigate if TREM2 had protective anti-inflammatory activity in AD. Data seemed to support the protective role of TREM2 in the preclinical stage of AD. In MCI-AD, up-regulation of TREM2 could be a mechanism to counteract the activation of neuroinflammatory processes. In the preclinical stage of AD, it seemed that TREM2 and ApoE ε4 could interact synergistically. Therefore, for the development of AD, TREM2 could be useful as an early peripheral biomarker .