Abstract
Alzheimer's disease (AD) is characterized by progressive cognitive decline and neuropathology, but its mechanisms remain incompletely understood. Impaired autophagy and overactivation of the NLRP3 inflammasome are thought to contribute to AD progression. Dihydromyricetin (DHM) is a natural flavonoid with known neuroprotective effects, yet it remains unclear whether DHM modulates the autophagy-lysosome pathway to suppress NLRP3 inflammasome activation and improve cognitive deficits. Here, we combined bioinformatics predictions with in vitro and in vivo experiments to investigate DHM's effects on autophagy and NLRP3 inflammasome signaling. Bioinformatic analysis of aging, AD, and cognition-related gene sets identified autophagy and immune regulation as key enriched pathways. Molecular docking predicted that DHM binds favorably to core autophagy and inflammasome proteins. In vitro, DHM (6.25-25 µg/mL) increased autophagy in BV2 microglia, as evidenced by an increased LC3-II/LC3-I ratio and ULK1 expression and reduced p62 accumulation, and markedly reduced LPS/ATP-induced upregulation of NLRP3, cleaved caspase-1, IL-1β, and IL-18. DHM also reduced LPS-induced intracellular ROS accumulation in BV2 cells and attenuated NF-κB p65 phosphorylation in SAMP8 hippocampus. In vivo, 8-week oral administration of DHM to senescence-accelerated mouse-prone 8 (SAMP8) mice, an accelerated aging model with AD-like cognitive and pathological features, enhanced hippocampal autophagy marker expression, reduced NLRP3 inflammasome-related proteins and AD-related pathological protein changes. Immunofluorescence and Western blot analyses showed that DHM increased the spatial association of NLRP3 with LC3- and LAMP1-positive structures, reduced ASC expression, and increased the lysosomal protease Cathepsin D. These molecular changes corresponded with improved spatial learning and memory in the Morris water maze. However, co-treatment with the autophagy inhibitor chloroquine (CQ) abolished the DHM's effects on autophagy markers, reversed its reduction of NLRP3-related inflammatory proteins, and negated its cognitive benefits. Taken together, these results suggest that DHM enhances autophagy-lysosome pathway activity and facilitates autophagy-associated suppression of NLRP3 inflammasome activation, thereby mitigating neuroinflammation and cognitive impairment in SAMP8 mice. This autophagy-dependent mechanism suggests that DHM, a well-tolerated natural compound, has potential as a multitarget therapeutic candidate for AD-like cognitive impairment.