Ciliatoside A attenuates neuroinflammation in Alzheimer's disease by activating mitophagy and inhibiting NLRP3 inflammasome activation

Abstract

Background: Alzheimer's disease (AD) is a gradually worsening neurological condition that involves memory loss, brain inflammation, and impaired mitochondrial function. The NLRP3 inflammasome activation in microglia plays a pivotal role in promoting neuroinflammation and worsening disease progression. Mitochondrial dysfunction and impaired mitophagy further create a detrimental feedback loop of oxidative stress and inflammation. Despite extensive research, pharmacological agents capable of simultaneously targeting both NLRP3 inflammasome activation and impaired mitophagy remain scarce.

Methods: We explored the therapeutic potential of Ciliatoside A (CA), a novel natural compound isolated from Peristrophe japonica, utilizing comprehensive cellular and animal models. In lipopolysaccharide/nigericin (LPS/Nig)-stimulated BV-2 microglial cells, the impact of CA on inflammasome activation, pyroptosis, mitochondrial health, and oxidative stress was assessed. Mechanistic evaluations were conducted using Western blotting, immunofluorescence, and advanced mitophagy assays. Furthermore, the efficacy of CA was validated in Caenorhabditis elegans (C. elegans) models expressing human amyloid-beta (Aβ) and the well-established 3xTg-AD mouse model.

Results: Our results demonstrate CA effectively inhibits NLRP3 inflammasome activation, reduces microglial pyroptosis, and mitigates oxidative stress-induced mitochondrial impairment in BV-2 cells. Notably, we identified the AMPK/ULK1 and PINK1/Parkin pathways as novel targets through which CA robustly activates mitophagy. Consistent therapeutic effects were observed in vivo, with CA significantly reducing Aβ-induced paralysis, ROS generation, and enhancing autophagy in worms. In 3xTg-AD mice, CA markedly improved cognitive function, diminished Aβ plaque deposition, alleviated neuroinflammation, and preserved neuronal integrity.

Conclusion: For the first time, this study reveals that CA offers dual neuroprotective benefits by promoting mitophagy while inhibiting NLRP3 inflammasome-mediated neuroinflammation. These novel insights highlight the innovative therapeutic potential of CA, suggesting its promising application in slowing AD progression and mitigating its pathological features.

Keywords: Alzheimer's disease; Ciliatoside A; Mitophagy; NLRP3 inflammasome; Neuroinflammation.