NRG1 Suppresses NLRP3 Inflammasome Activation and Endothelial-Mesenchymal Transition in Cerebral Ischemia-Reperfusion Injury: Association with the AKT/NF-κB Pathway.

BACKGROUND: Endothelial damage and NLRP3 inflammasome activation are key mechanisms underlying cerebral ischemia-reperfusion (I/R) injury. Neuregulin-1 (NRG1) alleviates endothelial damage, blood-brain barrier (BBB) disruption, and neurological deficits following acute ischemic stroke (AIS). This study investigates whether NRG1 attenuates endothelial-mesenchymal transition (EndMT) during endothelial injury by suppressing NLRP3 inflammasome activation, potentially through the AKT/NF-κB pathway, in cerebral I/R injury. METHODS: Middle cerebral artery occlusion/reperfusion (MCAO/R) mouse models and oxygen-glucose deprivation/reoxygenation (OGD/R)-treated immortalized human cerebral microvascular endothelial cells (hCMEC/D3) were established and treated with NRG1. Neurological deficits were assessed using the modified Neurological Severity Score (mNSS), while cerebral infarct volume and caspase-1 activity were quantified. Cell viability and death were evaluated by the Cell Counting Kit-8 (CCK-8), lactate dehydrogenase (LDH) assays, and TUNEL staining. Protein expression was analyzed using Western blotting and immunofluorescence staining. RESULTS: NRG1 intervention significantly improved mNSS, reduced cerebral infarct volume, and decreased caspase-1 activity in MCAO/R mice. In OGD/R-treated hCMEC/D3, NRG1 enhanced cell viability while reducing cell death, as indicated by decreased LDH release and TUNEL-positive cells. Western blotting and immunofluorescence staining revealed that NRG1 enhanced AKT phosphorylation, inhibited NF-κB p65 phosphorylation, and downregulated NLRP3 and IL-1β expression. These effects were associated with the amelioration of occludin reduction and suppression of α-smooth muscle actin (α-SMA) increase during EndMT progression. CONCLUSION: The results demonstrate that NRG1 reduces cerebral infarct volume, alleviates neurological deficits, and suppresses NLRP3 inflammasome activation in association with modulation of the AKT/NF-κB pathway, thereby attenuating EndMT-associated proteins following cerebral I/R injury.