Transcutaneous auricular vagus nerve stimulation attenuates post-stroke dysphagia by modulating microglial...

Post-stroke dysphagia is a common complication with limited treatment options. Transcutaneous auricular vagus nerve stimulation (ta-VNS) has shown neuroprotective effects. This study investigated whether ta-VNS improves swallowing function and alleviates neuroinflammation by modulating microglial M1/M2 polarization, examining the role of von Willebrand factor (VWF) in endothelial-microglial crosstalk. A rat model of transient bilateral middle cerebral artery occlusion (MCAO) was established. Rats received ta-VNS for 3 weeks, and swallowing function, neurological deficits, and inflammatory markers were assessed. Microglial M1 (CD16) and M2 (CD206) polarization in the white matter was examined by immunofluorescence. RNA-seq was used to identify candidate genes. In vitro, an oxygen-glucose deprivation/reoxygenation (OGD/R) model was applied to hCMEC/D3 endothelial cells co-cultured with HMC3 microglia, and VWF was knocked down using shRNA to evaluate its effect on microglial polarization and inflammation. ta-VNS significantly improved body weight, food/water intake, and swallowing function (reduced latency and increased swallowing frequency) in transient middle cerebral artery occlusion rats. ta-VNS reduced levels of TNF-α, IL-6, IL-1β, and IL-10, attenuated microglial activation, suppressed M1 (Iba-1⁺CD16⁺) microglia, and enhanced M2 (Iba-1⁺CD206⁺) polarization in rat whiter matter. RNA-seq revealed downregulation of VWF after ta-VNS, with enrichment in the PI3K-Akt pathway. In vitro, OGD/R upregulated VWF, ICAM-1, VCAM-1, endothelial apoptosis, and permeability. Knockdown of VWF in endothelial cells shifted co-cultured microglia from M1 toward M2 phenotype and reduced TNF-α, IL-6, and IL-1β while increasing IL-10. ta-VNS can improve post-stroke dysphagia and reduce neuroinflammation by promoting M2 microglial polarization. Endothelial VWF may be a key downstream mediator of this process.