TREM2 and Alzheimer disease: Beyond mediating microglial phagocytosis of Aβ and facilitating the conversion of plaque-resident microglia into the DAM subtype in the AD brain [18], previous studies also reported that Trem2 acts as a critical metabolic regulator that links lipid metabolism with effective microglial phagocytosis by maintaining the expression of key cholesterol-handling genes such as Abca1 and Abca7 under phagocytic challenges [62] [63].