Falvey Aidan, Palandira Santhoshi P, Chavan Sangeeta S, Brines Michael, Tracey Kevin J, Pavlov Valentin A
Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Northwell Health, 350 Community Drive, Manhasset, NY 11030, USA.
Elmezzi Graduate School of Molecular Medicine, 350 Community Drive, Manhasset, NY 11030, USA.
bioRxiv. 2023 May 20:2023.05.17.541191. doi: 10.1101/2023.05.17.541191.
The vagus nerve plays an important role in neuroimmune interactions and in the regulation of inflammation. A major source of efferent vagus nerve fibers that contribute to the regulation of inflammation is the brainstem dorsal motor nucleus of the vagus (DMN) as recently shown using optogenetics. In contrast to optogenetics, electrical neuromodulation has broad therapeutic implications, but the anti-inflammatory efficacy of electrical DMN stimulation (eDMNS) was not previously investigated. Here, we examined the effects of eDMNS on heart rate (HR) and cytokine levels in murine endotoxemia as well as the cecal ligation and puncture (CLP) model of sepsis.
Anesthetized male 8-10-week-old C57BL/6 mice on a stereotaxic frame were subjected to eDMNS using a concentric bipolar electrode inserted into the left or right DMN or sham stimulation. eDMNS (50, 250 or 500 μA and 30 Hz, for 1 min) was performed and HR recorded. In endotoxemia experiments, sham or eDMNS utilizing 250 μA or 50 μA was performed for 5 mins and was followed by LPS (0.5 mg/kg) i.p. administration. eDMNS was also applied in mice with cervical unilateral vagotomy or sham operation. In CLP experiments sham or left eDMNS was performed immediately post CLP. Cytokines and corticosterone were analyzed 90 mins after LPS administration or 24h after CLP. CLP survival was monitored for 14 days.
Either left or right eDMNS at 250 μA and 500 μA decreased HR, compared with pre- and post-stimulation. This effect was not observed at 50 μA. Left side eDMNS at 50 μA, compared with sham stimulation, significantly decreased serum and splenic levels of the pro-inflammatory cytokine TNF and increased serum levels of the anti-inflammatory cytokine IL-10 during endotoxemia. The anti-inflammatory effect of eDMNS was abrogated in mice with unilateral vagotomy and were not associated with serum corticosterone alterations. Right side eDMNS suppressed serum TNF levels but had no effects on serum IL-10 and on splenic cytokines. In mice with CLP, left side eDMNS suppressed serum TNF and IL-6, as well as splenic IL-6 and increased splenic IL-10 and significantly improved the survival rate of CLP mice.
For the first time we show that a regimen of eDMNS which does not cause bradycardia alleviates LPS-induced inflammation and these effects require an intact vagus nerve and are not associated with corticosteroid alterations. eDMNS also decreases inflammation and improves survival in a model of polymicrobial sepsis. These findings are of interest for further studies exploring bioelectronic anti-inflammatory approaches targeting the brainstem DMN.
迷走神经在神经免疫相互作用和炎症调节中发挥重要作用。最近利用光遗传学研究表明，参与炎症调节的传出迷走神经纤维的一个主要来源是脑干迷走神经背运动核（DMN）。与光遗传学不同，电神经调节具有广泛的治疗意义，但此前尚未研究过电刺激DMN（eDMNS）的抗炎功效。在此，我们研究了eDMNS对小鼠内毒素血症以及盲肠结扎和穿刺（CLP）脓毒症模型中心率（HR）和细胞因子水平的影响。
将8 - 10周龄麻醉的雄性C57BL/6小鼠置于立体定位框架上，使用插入左或右DMN的同心双极电极进行eDMNS或假刺激。进行eDMNS（50、250或500 μA，30 Hz，持续1分钟）并记录HR。在内毒素血症实验中，进行假刺激或使用250 μA或50 μA的eDMNS持续5分钟，随后腹腔注射LPS（0.5 mg/kg）。eDMNS也应用于单侧颈迷走神经切断或假手术的小鼠。在CLP实验中，CLP后立即进行假刺激或左侧eDMNS。在注射LPS后90分钟或CLP后24小时分析细胞因子和皮质酮。监测CLP小鼠的存活14天。
与刺激前和刺激后相比，250 μA和500 μA的左侧或右侧eDMNS均降低了HR。50 μA时未观察到这种效应。在内毒素血症期间，与假刺激相比，50 μA的左侧eDMNS显著降低了促炎细胞因子TNF的血清和脾脏水平，并增加了抗炎细胞因子IL - 10的血清水平。eDMNS的抗炎作用在单侧迷走神经切断的小鼠中被消除，且与血清皮质酮变化无关。右侧eDMNS抑制血清TNF水平，但对血清IL - 10和脾脏细胞因子无影响。在CLP小鼠中，左侧eDMNS抑制血清TNF和IL -
