IRE1α inhibition attenuates neuronal pyroptosis via miR-125/NLRP1 pathway in a neonatal hypoxic-ischemic encephalopathy rat model

BackgroundInhibition of inositol-requiring enzyme-1 alpha (IRE1 alpha), one of the sensor signaling proteins associated with endoplasmic reticulum (ER) stress, has been shown to alleviate brain injury and improve neurological behavior in a neonatal hypoxic-ischemic encephalopathy (HIE) rat model. However, there is no information about the role of IRE1 alpha inhibitor as well as its molecular mechanisms in preventing neuronal pyroptosis induced by NLRP1 (NOD-, LRR- and pyrin domain-containing 1) inflammasome. In the present study, we hypothesized that IRE1 alpha can degrade microRNA-125-b-2-3p (miR-125-b-2-3p) and activate NLRP1/caspased-1 pathway, and subsequently promote neuronal pyroptosis in HIE rat model.MethodsTen-day old unsexed rat pups were subjected to hypoxia-ischemia (HI) injury, and the inhibitor of IRE1 alpha, STF083010, was administered intranasally at 1h after HI induction. AntimiR-125 or NLRP1 activation CRISPR was administered by intracerebroventricular (i.c.v) injection at 24h before HI induction. Immunofluorescence staining, western blot analysis, reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR), brain infarct volume measurement, neurological function tests, and Fluoro-Jade C staining were performed.ResultsEndogenous phosphorylated IRE1 alpha (p-IRE1 alpha), NLRP1, cleaved caspase-1, interleukin-1 beta (IL-1 beta), and interleukin-18 (IL-18) were increased and miR-125-b-2-3p was decreased in HIE rat model. STF083010 administration significantly upregulated the expression of miR-125-b-2-3p, reduced the infarct volume, improved neurobehavioral outcomes and downregulated the protein expression of NLRP1, cleaved caspase-1, IL-1 beta and IL-18. The protective effects of STF083010 were reversed by antimiR-125 or NLRP1 activation CRISPR.ConclusionsIRE1 alpha inhibitor, STF083010, reduced neuronal pyroptosis at least in part via miR-125/NLRP1/caspase-1 signaling pathway after HI.