Ginsenoside Rd attenuates cerebral ischemia/reperfusion injury by exerting an anti-pyroptotic effect via the miR-139-5p/FoxO1/Keap1/Nrf2 axis

Pyroptosis mediated by nucleotide-binding oligomerization domain (NOD)-like receptor 3 (NLRP3) inflammasome is implicated in cerebral ischemia/reperfusion (I/R) injury. Ginsenoside Rd (Rd), a monomer component of Panax ginseng and Panax notoginseng, is reported to confer neuroprotection in brain injury models. However, the role of pyroptosis in Rd-mediated neuroprotection following cerebral I/R has not been investigated. We aimed to confirm the neuroprotective function and underlying mechanisms of Rd on pyroptosis after cerebral I/R using a middle cerebral artery occlusion/reperfusion (MCAO/R) model in male C57BL/6 mice, and oxygen-glucose deprivation/reoxygenation (OGD/R) model in primary cortical neurons. MicroRNA-139-5p (miR-139-5p) downregulation, forkhead box transcription factor O1 (FOXO1) and Kelch-like ECH-associated protein 1 (Keap1) upregulation, nuclear factor erythroid-2 related factor 2 (Nrf2) antioxidant pathway inactivation, reactive oxygen species (ROS)-driven thioredoxin-interacting protein (TXNIP) over-expression, and NLRP3 inflammasome activation-induced pyroptosis were observed in ischemic cortical tissues and primary neurons under MCAO/R and OGD/R induction. More importantly, Rd upregulated miR-139-5p to inhibit FoxO1 which regulates Keap1 transcriptional activity, and subsequently activates the Nrf2 antioxidant pathway, resulting in attenuation of ROS/TXNIP/NLRP3 inflammasome axis-driven pyroptosis in these animal and cell models. In summary, an anti-pyroptotic effect via the miR-139-5p/FoxO1/Keap1/Nrf2 axis may be the mechanism by which Rd attenuates ischemic stroke.