14,15-EET Maintains Mitochondrial Homeostasis to Inhibit Neuronal Pyroptosis After Ischemic Stroke

BACKGROUND: Neuronal pyroptosis is involved in neuronal cell death and neurological damage after cerebral ischemia-reperfusion. 14,15-Epoxyeicosatrienoic acid (14,15-EET) can reduce neuronal loss induced by cerebral ischemia-reperfusion by regulating mitochondrial biological processes. However, it remains unclear how 14,15-EET regulates mitochondrial homeostasis, inhibits neuronal pyroptosis, and promotes neurological functional recovery after cerebral ischemia-reperfusion. METHODS: Mice with middle cerebral artery occlusion and reperfusion were used as an animal model to study the cerebral ischemia-reperfusion disease. The neurological function of mice was performed at 1, 3, and 5 days to test the therapeutic effects of 14,15-EET. Transmission electron microscope imaging and Nissl staining were used to analyze neuronal morphological structure, mitophagy, and neuronal pyroptosis. Western blot and transcriptome were used to detect the levels of mitophagy and neuronal pyroptosis signaling pathway–related molecules. HT22 cells were used in in vitro studies to detect the mechanism by which 14,15-EET reduces neuronal pyroptosis after oxygen-glucose deprivation/reoxygenation treatment. RESULTS: 14,15-EET treatment reduced cerebral infarct volumes and improved neurological functional recovery in mice after cerebral ischemia-reperfusion. 14,15-EET treatment maintained the morphological structure of neurons in the ischemic penumbra area as well as the dendritic spine density in mice after cerebral ischemia-reperfusion. The upregulation of NLRP1 (NOD-like receptor thermal protein domain associated protein 1), IL (interleukin)-1β, caspase-1, and GSDMD (gasdermin D) induced by cerebral ischemia-reperfusion was inhibited, and the expression of mitophagy proteins Parkin and LC3B (microtubule-associated protein 1 light chain 3 B) was increased by 14,15-EET treatment. Transcriptome profiling found that 14,15-EET exerts a neuroprotection role in promoting neural function recovery by activating the WNT (wingless-type mouse mammary tumor virus integration site family) signaling pathway. We found that 14,15-EET upregulated the WNT pathway proteins such as WNT1, WNT3A, β-catenin, and p-GSK-3β (phosphorylation of glycogen synthase kinase 3β) in vivo and in vitro. The WNT signaling pathway inhibitor XAV-939 reduced the expression of mitophagy protein Parkin and upregulated the expression of caspase-1 and GSDMD in HT22 cells with oxygen-glucose deprivation/reoxygenation and 14,15-EET treatment. CONCLUSIONS: 14,15-EET regulates mitochondrial homeostasis to inhibit neuronal pyroptosis, thereby promoting the recovery of neurological function in mice after cerebral ischemia-reperfusion. These results provide new ideas for maintaining mitochondrial homeostasis and inhibiting neuronal pyroptosis after cerebral ischemia-reperfusion.