Background

Alzheimer's disease (AD) is closely related to neuroinflammation and endoplasmic reticulum (ER) stress. Abnormal accumulation of amyloid-β (Aβ) induces ER stress, activating astrocytes through the nuclear factor kappa-B (NF-κB) pathway and ultimately causing neuroinflammation and neuronal injury. Therefore, targeting the modulation of the ER stress-inflammatory cycle and normalizing astrocyte function could be a potential strategy for AD. Recent studies indicate that artemisinin (ART) has significant neuroprotective effects. However, the mechanism by which artemisinin regulates astrocyte activation to improve AD process requires further exploration.

Methods

We used Aβ1-42 induced A172 cells or primary astrocytes as an in vitro model and 3×Tg-AD mice as an in vivo model to investigate the potential therapeutic effects and mechanism of ART on AD. Western blot and immunofluorescence was used to measure the protein level related to ER stress and neuroinflammation. RT-qPCR was used to detect the mRNA level of neurotrophic factors and inflammation cytokines. To explore specific mechanism of ART on astrocyte, IRE1 expression was mediated at the drug and gene level in vitro and in vivo.

Results

Exposure of A172 cells to Aβ1-42 induced astrocyte activation, ER stress, and inflammatory responses. ART treatment attenuated these effects, specifically inhibiting IRE1 phosphorylation and downstream NF-κB signaling. ART also restored the neurotrophic function of astrocytes, protecting primary neurons from Aβ1-42 toxicity. The IRE1 kinase inhibitor KIRA6 reversed the toxic effects of Aβ1-42 on astrocytes. In further studies, we demonstrated that ART relied on IRE1 kinase activity to prevent Aβ1-42-induced astrocyte overactivation. Additionally, ART restored the phosphatase activity of protein phosphatase 2A (PP2A), inhibiting IRE1 phosphorylation. In 3×Tg-AD mice, ART reduced IRE1-mediated downstream inflammatory signals, alleviated astrocyte overactivation, and rescued neuronal apoptosis. Pharmacological interventions in the mouse model further supported ART's therapeutic potential by demonstrating improvements in cognitive function and reduced neuroinflammation. Importantly, AAV-mediated IRE1 overexpression in astrocytes abrogated the beneficial effects of ART.

Conclusion

Our study demonstrates that artemisinin exerts neuroprotective effects by modulating the IRE1-ER stress pathway in astrocytes, reducing neuroinflammation, and ameliorating cognitive deficits in an AD mouse model. These findings provide insights into the potential therapeutic value of artemisinin in AD.