APOE and Alzheimer disease: Various reports have suggested the involvement of the complement production and signaling (C1, C1q, C3, CR1, Factor B, Factor D, and Properdin), NLRP3 inflammasome activation (VRAC, NLRP3 P2X7,), and TREM2/DAP12 signaling (TREM2, PLCγ2, SHIP-1, and Apolipoprotein E) in the regulation of microglial survival and proliferation, actin cytoskeleton polarization, cytoskeleton organization, stimulating microglial phagocytosis, cytokine production, immune responses, and could be potential therapeutic targets in modulating microglial functions for AD (Konishi and Kiyama, 2018; Mecca et al., 2018).