STAT3 Suppression by Rutin Attenuates the Neurotoxic Effect of Pro-Inflammatory Microglia on Neurons Under Oxygen-Glucose Deprivation

Background and Objective: The microglia-mediated neuroinflammatory response significantly contributes to neuronal damage following ischemic stroke by activating the signal transducer and activator of transcription 3 (STAT3) signal pathway. Rutin has been shown to exhibit STAT3-inhibitory properties, yet the effects of rutin on microglial polarization under ischemic context remain insufficiently understood. Therefore, this study aimed to investigate the effects of rutin on microglial activation and neuroprotection under oxygen-glucose deprivation (OGD) conditions and to elucidate the underlying mechanism. Materials and Methods: Neuro-2a cells were subjected to OGD, and the subsequent conditioned medium (CM) was collected, and used to stimulate BV2 cells in vitro. The impact of rutin on microglial activation was assessed by analyzing cytokine profiles and microglial polarization. STAT3 phosphorylation was detected by Western immunoblot analysis, and the potential binding sites of rutin and STAT3 were determined through in silico molecular docking analysis. Neuron-microglia co-culture systems were employed to evaluate neuroprotective effects through viability and apoptosis assays. Results: Microglia cultured with CM exhibited increased pro-inflammatory cytokines and M1 polarization, which were reversed by rutin treatment. Additionally, rutin significantly promoted anti-inflammatory microglial polarization in a hypoxic condition through a decrease in phosphorylated STAT3 levels. These effects were demonstrated in a dose-dependent manner. Notably, OGD-challenged neurons exhibited enhanced survival and reduced apoptosis when co-cultured with rutin and CM-treated microglia. Conclusion: Rutin offers neuroprotection by modulating microglial activation towards an anti-inflammatory phenotype, which is associated with the STAT3 pathway, underscoring the potential of rutin as a therapeutic agent for ischemic stroke and related cerebral injury.