DNA Sensing Pathways in Innate Immunity: Implications for Alzheimer's Disease Progression and Therapy

DNA sensors are emerging regulators of innate immune activation in Alzheimer's disease (AD). In addition to detecting microbial DNA, these pattern-recognition receptors can respond to cytosolic or endosomal self-DNA generated by DNA damage, mitochondrial dysfunction, impaired DNA repair, cellular stress, or neuronal injury. Aberrant activation of DNA-sensing pathways may amplify neuroinflammation through type I interferon (IFN-I) signaling, inflammasome activation, pyroptosis, and microglial dysfunction, thereby contributing to amyloid pathology, tau-related inflammation, synaptic loss, and cognitive decline. In this review, we summarize current evidence linking major DNA sensors, including cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING), absent in melanoma 2 (AIM2), toll-like receptor 9 (TLR9) to AD pathogenesis. We emphasize the strongest available evidence for cGAS-STING and AIM2, discuss the context-dependent roles of TLR9, and highlight less-established sensors requiring further validation. Finally, we evaluate therapeutic strategies targeting DNA-sensing pathways, including pathway inhibition and controlled immune activation, and discuss translational challenges such as blood-brain barrier penetration, off-target effects, dose dependency, and disease-stage-specific modulation.