PARK7-Nrf2 axis mitigates NLRP3-driven inflammation to rescue neurovascular unit from hypoxia/reoxygenation-induced necroptosis

In the ischemic penumbra, necroptosis-induced inflammation exacerbates neurovascular unit (NVU) injury, though neuronal self-regulatory mechanisms are poorly understood. This study examined whether the PARK7–Nrf2 axis, a key antioxidant pathway, alleviates NLRP3-driven inflammation during necroptosis to protect the NVU. This study integrated a rat middle cerebral artery occlusion/reperfusion (MCAO/R) model in vivo and an in vitro model of primary cortical neuronal necroptosis induced by oxygen-glucose deprivation/reoxygenation (OGD/R) combined with the pan-caspase inhibitor Q-VD-Oph. Lentivirus-mediated gene knockdown and overexpression, pharmacological interventions including specific inhibitors (Nec-1), activators (tBHQ), and the protein translation inhibitor CHX were employed. These were combined with molecular biology techniques such as Western blot, immunofluorescence, co-immunoprecipitation, and RT-qPCR to systematically dissect the role and regulatory mechanisms of PARK7. Hypoxia/reoxygenation injury robustly activated neuronal necroptosis, which subsequently triggered the assembly and activation of the NLRP3 inflammasome, leading to NVU disruption. Notably, PARK7 expression was significantly upregulated post-hypoxia/reoxygenation. Mechanistically, PARK7 directly enhanced Nrf2 activation through a dual mechanism: facilitating the dissociation of Nrf2 from Keap1 and promoting its nuclear translocation, while simultaneously stabilizing the Nrf2 protein and reducing its degradation. Activated Nrf2 subsequently upregulated the expression of downstream antioxidant proteins NQO1 and HO-1. This PARK7-Nrf2 signaling axis effectively suppressed the NLRP3 inflammasome and its associated inflammatory cascade. Consequently, PARK7 overexpression significantly alleviated NVU damage, reduced cerebral infarct volume, and improved neurological function, whereas PARK7 knockdown exacerbated these injuries. The detrimental effects caused by PARK7 deficiency were reversed by the Nrf2 activator tBHQ. This study reveals that PARK7 activates the Nrf2/ARE pathway, via promoting Nrf2-Keap1 dissociation and stabilizing Nrf2, to inhibit necroptosis-driven NLRP3 inflammasome overactivation in the ischemic penumbra. This mechanism provides a novel regulatory pathway for inflammation and highlights the PARK7/Nrf2 axis as a therapeutic target to mitigate neurovascular unit injury, thereby extending the treatment window and enabling a combined recanalization-cytoprotection strategy with significant translational promise.