Electronic nicotine delivery systems, or e.cigarettes utilise a liquid solution that normally contains propylene glycol (PG) and vegetable glycerine (VG) to generate vapour and act as a carrier for nicotine and flavourings. Evidence indicated these 'carriers' reduced growth and survival of epithelial cells including those of the airway. We hypothesised that 3% PG or PG mixed with VG (3% PG:VG, 55:45) inhibited glucose uptake in human airway epithelial cells as a first step to reducing airway cell survival. Exposure of H441 or human bronchiolar epithelial cells (HBEC) to PG and PG/VG (30-60 minutes) inhibited glucose uptake and mitochondrial ATP synthesis. PG/VG inhibited glycolysis. PG/VG and mannitol reduced cell volume and height of air-liquid interface cultures. Mannitol but not PG/VG increased phosphorylation of p38 MAPK. PG/VG reduced TEER which was associated with increased transepithelial solute permeability. PG/VG decreased FRAP of GFP linked glucose transporters GLUT1 and GLUT10 indicating that glucose transport function was compromised. Puffing PG/VG vapour onto the apical surface of primary HBEC for 10 mins to mimic the effect of e.cigarette smoking also reduced glucose transport. In conclusion, short term exposure to PG/VG, key components of e.cigarettes, decreased glucose transport and metabolism in airway cells. We propose that this was a result of PG/VG reduced cell volume and membrane fluidity, with further consequences on epithelial barrier function. Taken together, we suggest these factors contribute to reduced defensive properties of the epithelium. We propose that repeated/chronic exposure to these agents are likely to contribute to airway damage in e-cigarette users.

中文翻译：

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电子烟成分丙二醇和植物甘油降低葡萄糖摄取及其在体外气道上皮细胞中的代谢

电子尼古丁输送系统或电子香烟利用通常含有丙二醇 (PG) 和植物甘油 (VG) 的液体溶液来产生蒸汽并充当尼古丁和调味剂的载体。有证据表明，这些“携带者”减少了上皮细胞（包括气道细胞）的生长和存活。我们假设 3% PG 或 PG 与 VG 混合（3% PG:VG，55:45）抑制人气道上皮细胞的葡萄糖摄取，这是降低气道细胞存活率的第一步。H441 或人细支气管上皮细胞 (HBEC) 暴露于 PG 和 PG/VG（30-60 分钟）会抑制葡萄糖摄取和线粒体 ATP 合成。PG/VG 抑制糖酵解。PG/VG 和甘露醇减少了气液界面培养物的细胞体积和高度。甘露醇而非 PG/VG 增加了 p38 MAPK 的磷酸化。PG/VG 降低了与跨上皮溶质渗透性增加相关的 TEER。PG/VG 降低了 GFP 连接的葡萄糖转运蛋白 GLUT1 和 GLUT10 的 FRAP，表明葡萄糖转运功能受损。将 PG/VG 蒸汽喷到初级 HBEC 的顶端表面 10 分钟以模拟电子烟吸烟的效果也减少了葡萄糖转运。总之，短期接触 PG/VG（电子烟的关键成分）会降低气道细胞中的葡萄糖转运和代谢。我们认为这是 PG/VG 减少细胞体积和膜流动性的结果，对上皮屏障功能有进一步的影响。总之，我们认为这些因素有助于降低上皮的防御特性。