Department of Rehabilitation, The Second Affiliated Hospital of Chongqing Medical University, 76 Linjiang Road, Yuzhong District, Chongqing 400010, China; Chongqing Medical University, Yixueyuan Road, Yuzhong District, Chongqing 40010, China.
Department of Rehabilitation, The Second Affiliated Hospital of Chongqing Medical University, 76 Linjiang Road, Yuzhong District, Chongqing 400010, China; Chongqing Medical University, Yixueyuan Road, Yuzhong District, Chongqing 40010, China.
J Stroke Cerebrovasc Dis. 2022 Sep;31(9):106596. doi: 10.1016/j.jstrokecerebrovasdis.2022.106596. Epub 2022 Jul 11.
To specify the effect of vagus nerve stimulation (VNS) on microglial polarization following ischemic-reperfusion and further investigate its underlying mechanism.
Sprague-Dawley rats were randomly divided into the sham, ischemic reperfusion group (IR), IR+VNS groups. VNS intervention lasting for 1 hour was administered after 30 minutes of occlusion. We analyzed the expression of Arginase 1 (Arg1), the number of M2 microglial in the peri-infarction cortex and assessed the neurological scores at the 1, 3, 7 days after reperfusion to determine the research time point. Then, we assessed polarization status of microglial, the infarct volume, neurological scores, the cellular distribution of Toll-like Receptor 4 (TLR4), the TLR4-associated pathway protein and the p-NF-κB in microglial at 3 days after reperfusion.
We found that VNS could increase the specific marker of M2 Arg1 and upregulate the M2 microglial after reperfusion, and the increase of Arg1, M2 microglial and the neurological scores was largest at the 3 days after reperfusion. VNS treatment significantly reduced the number and percent of M1, improved the number and percent of M2 and upregulated the M2 to M1 ratio without changing the number of total microglial at the 3 days after reperfusion. Moreover, VNS reduced the infarct volume and neurological deficits. In addition, VNS significantly reduced the microglial-specific TLR4, inhibited the activated TLR4/MyD88/NF-κB pathway following ischemic-reperfusion, and ultimately suppressed the p-NF-κB in microglial.
Our study revealed that VNS can promote the M1-to-M2 phenotype conversion to alleviate inflammatory response and brain injury through inhibition of TLR4/MyD88/NF-κB pathway in microglia following ischemic-reperfusion.
明确迷走神经刺激（VNS）对缺血再灌注后小胶质细胞极化的影响，并进一步探讨其潜在机制。
将 Sprague-Dawley 大鼠随机分为假手术组、缺血再灌注组（IR）和 IR+VNS 组。在闭塞 30 分钟后进行 1 小时的 VNS 干预。我们分析了梗死周围皮质中 Arg1（Arg1）的表达、M2 小胶质细胞的数量，并在再灌注后 1、3、7 天评估神经评分，以确定研究时间点。然后，我们评估了再灌注后 3 天小胶质细胞极化状态、梗死体积、神经评分、Toll 样受体 4（TLR4）的细胞分布、TLR4 相关通路蛋白和小胶质细胞中的 p-NF-κB。
我们发现，VNS 可以增加再灌注后 M2 的特异性标记物 Arg1，并上调 M2 小胶质细胞，其中 Arg1、M2 小胶质细胞和神经评分的增加在再灌注后 3 天最大。VNS 治疗可显著减少 M1 的数量和比例，增加 M2 的数量和比例，并上调 M2 与 M1 的比值，而不改变再灌注后 3 天小胶质细胞的总数。此外，VNS 可降低梗死体积和神经功能缺损。此外，VNS 还显著降低了小胶质细胞特异性 TLR4，抑制了缺血再灌注后激活的 TLR4/MyD88/NF-κB 通路，并最终抑制了小胶质细胞中的 p-NF-κB。
本研究表明，VNS 可通过抑制缺血再灌注后小胶质细胞 TLR4/MyD88/NF-κB 通路，促进 M1 向 M2 表型转化，从而减轻炎症反应和脑损伤。
