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Research Article: Neuronal exosomal miR-25-3p attenuates M1 microglial activation and neurotoxicity by targeting TLR4 to regulate the NF-?B signaling pathway

Date Published: 2026-06-03

Abstract:
Perioperative neurocognitive disorders (PND) are severe postoperative complications in the elderly, with neuroinflammation driven by pro-inflammatory M1 microglia being a core pathological mechanism. This study aimed to investigate the role of neuron-derived exosomes in regulating microglial polarization and its underlying molecular mechanism. We utilized a neuron–microglia transwell co-culture system. By modulating microRNA-25-3p (miR-25-3p) in neurons or Toll-like receptor 4 (TLR4) in microglia, we assessed microglial M1/M2 polarization, TLR4/NF-?B pathway activation, and subsequent neurotoxicity using qRT-PCR, Western Blot, flow cytometry, and dual-luciferase reporter assays. Neuronal exosomes were effectively internalized by microglia. Exosomal miR-25-3p suppressed the activation of the TLR4/MyD88/NF-?B signaling pathway by directly targeting the 3’-UTR of TLR4. This significantly inhibited microglial polarization towards the pro-inflammatory M1 phenotype and reduced the release of pro-inflammatory cytokines. Functionally, this process attenuated M1 microglia-mediated neuronal apoptosis, oxidative stress, and functional impairment. Direct manipulation of TLR4 expression in microglia confirmed its pivotal role in this regulatory axis. Our findings systematically demonstrate that neurons can release exosomes carrying miR-25-3p to target and suppress the microglial TLR4/NF-?B signaling pathway, thereby inhibiting M1 polarization and alleviating neurotoxicity. This discovery deepens the understanding of PND pathophysiology and provides a theoretical basis and potential therapeutic targets for novel PND treatment strategies targeting neuron–glia communication.

Introduction:
Perioperative neurocognitive disorders (PND) are severe postoperative complications in the elderly, with neuroinflammation driven by pro-inflammatory M1 microglia being a core pathological mechanism. This study aimed to investigate the role of neuron-derived exosomes in regulating microglial polarization and its underlying molecular mechanism.

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