TREM2 and microglial immunity in Alzheimer's disease: mechanisms, genetics, and therapeutic opportunities.

Alzheimer's disease (AD) is increasingly recognized as a disorder of innate immune dysregulation within the central nervous system. The triggering receptor expressed on myeloid cells 2 (TREM2), a microglial immunoreceptor, has emerged as a pivotal genetic risk factor for late-onset AD, underscoring the critical role of neuroimmune interactions in disease pathogenesis. This review synthesizes recent advances concerning TREM2's modulation of core microglial functions, including phagocytosis, inflammatory signaling, cellular metabolism, and survival, processes that are essential for responding to amyloid-β plaques and neuronal damage. We highlight the TREM2-APOE pathway as a central mechanism driving the disease-associated microglia (DAM) phenotype and examine how loss-of-function mutations such as