TREM2 and Alzheimer disease: In AD, another major risk factor, triggering receptor expressed on myeloid cells 2 (TREM2), increases microglial phagocytosis of Aβ, and also exerts anti-inflammatory effect on Toll-like receptor (TLR) activation (Guerreiro et al., 2013; Jonsson et al., 2013; Liu et al., 2020).