Innate immune sensing of Z-nucleic acids by ZBP1-RIPK1 axis drives neuroinflammation in Alzheimer's disease

Abstract

Neuroinflammation drives Alzheimer's disease (AD) pathogenesis. Z-DNA, a non-canonical left-handed DNA structure, activates innate immune signaling through Z-DNA-binding protein 1 (ZBP1). However, the functional significance of ZBP1-mediated Z-DNA detection in AD remains undefined. Here, we found that ZBP1 is amplified in AD microglia, driving innate immune responses and neuroinflammation through sensing Z-form mitochondrial DNA (mtDNA). We show that oxidized mtDNA, generated by amyloid-β (Aβ)-induced oxidative stress, was fragmented and released into the cytoplasm, forming Z-DNA. Z-DNA-activated ZBP1 engaged receptor-interacting protein kinase 1 (RIPK1), promoting its kinase activation and inducing transcription of pro-inflammatory molecules and inflammatory signaling mediators. Genetic deletion of Zbp1 or inhibition of RIPK1 attenuated neuroinflammation, Aβ pathology, and behavioral deficits in an AD mouse model. Our findings reveal that oxidation induces the Z conformer in mtDNA and establish the ZBP1-RIPK1 axis as a key driver of AD neuroinflammation, providing insights into the immune mechanisms underlying AD pathogenesis and identifying a potential therapeutic target.

Keywords: 8-oxoguanine; Alzheimer's disease; DNA fragmentation; RIPK1; Z-DNA; ZBP1; amyloid-β; mitochondrial DNA; neuroinflammation; oxidative stress.