The controversial contribution of microglia to AD pathogenesis is discussed by a growing body of literature, with molecules such as CX3CR1, APOE and triggering receptor expressed by myeloid cells 2 (TREM2) showing a critical impact on disease evolution by regulating phagocytosis and anti-inflammatory signaling in macrophages/microglia (352–355). Here, TREM2 is linked to Alzheimer disease.