Abstract / Summary
Abstract Background: Postoperative cognitive dysfunction (POCD) is a debilitating neurological complication in elderly patients, with neuroinflammation driven by microglial activation playing a central role. Lipocalin-2 (LCN2), an iron-binding protein, is involved in various CNS pathologies, yet its specific role and upstream regulation in POCD remain poorly understood. Methods: Aged C57BL/6J mice underwent unilateral nephrectomy to establish the POCD model. Adeno-associated virus (AAV)-mediated LCN2 knockdown was employed to evaluate its therapeutic potential. Cognitive function was assessed via the novel object recognition (NOR) and Y-maze tests. In vitro, BV2 microglia and HT-22 neurons were used to dissect the TLR3-LCN2 signaling cascade using the TLR3 agonist Poly(I:C), the iron chelator deferoxamine (DFO), and LCN2 inhibitors. Results: Surgical stress significantly induced cognitive impairment, accompanied by upregulated TLR3 and LCN2 expression and a shift toward pro-inflammatory M1 microglial polarization in the hippocampus. Genetic knockdown of LCN2 markedly attenuated M1 polarization, reduced neuronal pyroptosis, and rescued cognitive deficits in aged mice. Mechanistically, TLR3 activation triggered LCN2 expression, which subsequently facilitated intracellular iron accumulation and reactive oxygen species (ROS) production, driving M1 polarization. Furthermore, pharmacological inhibition of the iron-ROS pathway by DFO effectively suppressed LCN2-induced M1 polarization. Microglia-neuron co-culture assays confirmed that M1-polarized microglia promoted GSDMD-dependent neuronal pyroptosis. Conclusion: Our findings demonstrate that the TLR3-LCN2 axis exacerbates POCD by driving iron-ROS-mediated microglial M1 polarization and subsequent neuronal pyroptosis. Targeting LCN2 or the iron-ROS pathway offers a promising immunopharmacological strategy for alleviating postoperative neurocognitive impairment.