Azuelos Ilan, Jung Boris, Picard Martin, Liang Feng, Li Tong, Lemaire Christian, Giordano Christian, Hussain Sabah, Petrof Basil J
From the Meakins Christie Laboratories and Respiratory Division, McGill University Health Centre Research Institute, Montreal, Quebec, Canada (I.A., B.J., F.L., T.L., C.L., C.G., S.H., B.J.P.); Department of Critical Care Medicine and Anesthesiology, Saint Eloi Teaching Hospital, Montpellier, France, and Centre National de la Recherche Scientifique (CNRS 9214), Institut National de la Santé et de la Recherche Médicale (INSERM U-1046), Montpellier University, Montpellier, France (B.J.); Center for Mitochondrial and Epigenomic Medicine, Children's Hospital of Philadelphia and University of Pennsylvania, Philadelphia, Pennsylvania (M.P.); and Department of Critical Care, McGill University Health Centre, Montreal, Quebec, Canada (S.H.).
Anesthesiology. 2015 Jun;122(6):1349-61. doi: 10.1097/ALN.0000000000000656.
Mechanical ventilation (MV) is associated with atrophy and weakness of the diaphragm muscle, a condition termed ventilator-induced diaphragmatic dysfunction (VIDD). Autophagy is a lysosomally mediated proteolytic process that can be activated by oxidative stress, which has the potential to either mitigate or exacerbate VIDD. The primary goals of this study were to (1) determine the effects of MV on autophagy in the diaphragm and (2) evaluate the impact of antioxidant therapy on autophagy induction and MV-induced diaphragmatic weakness.
Mice were assigned to control (CTRL), MV (for 6 h), MV + N-acetylcysteine, MV + rapamycin, and prolonged (48 h) fasting groups. Autophagy was monitored by quantifying (1) autophagic vesicles by transmission electron microscopy, (2) messenger RNA levels of autophagy-related genes, and (3) the autophagosome marker protein LC3B-II, with and without administration of colchicine to calculate the indices of relative autophagosome formation and degradation. Force production by mouse diaphragms was determined ex vivo.
Diaphragms exhibited a 2.2-fold (95% CI, 1.8 to 2.5) increase in autophagic vesicles visualized by transmission electron microscopy relative to CTRL after 6 h of MV (n = 5 per group). The autophagosome formation index increased in the diaphragm alone (1.5-fold; 95% CI, 1.3 to 1.8; n = 8 per group) during MV, whereas prolonged fasting induced autophagosome formation in both the diaphragm (2.5-fold; 95% CI, 2.2 to 2.8) and the limb muscle (4.1-fold; 95% CI, 1.8 to 6.5). The antioxidant N-acetylcysteine further augmented the autophagosome formation in the diaphragm during MV (1.4-fold; 95% CI, 1.2 to 1.5; n = 8 per group) and prevented MV-induced diaphragmatic weakness. Treatment with the autophagy-inducing agent rapamycin also largely prevented the diaphragmatic force loss associated with MV (n = 6 per group).
In this model of VIDD, autophagy is induced by MV but is not responsible for diaphragmatic weakness. The authors propose that autophagy may instead be a beneficial adaptive response that can potentially be exploited for therapy of VIDD.
机械通气（MV）与膈肌萎缩和无力相关，这种情况被称为呼吸机诱发的膈肌功能障碍（VIDD）。自噬是一种由溶酶体介导的蛋白水解过程，可被氧化应激激活，其有可能减轻或加重VIDD。本研究的主要目的是：（1）确定MV对膈肌自噬的影响；（2）评估抗氧化治疗对自噬诱导和MV诱发的膈肌无力的影响。
将小鼠分为对照组（CTRL）、MV组（6小时）、MV + N - 乙酰半胱氨酸组、MV + 雷帕霉素组和长期（48小时）禁食组。通过以下方法监测自噬：（1）用透射电子显微镜定量自噬小泡；（2）检测自噬相关基因的信使核糖核酸水平；（3）检测自噬体标记蛋白LC3B - II，在给予和不给予秋水仙碱的情况下计算相对自噬体形成和降解的指标。离体测定小鼠膈肌的力量产生。
与CTRL组相比，MV 6小时后，透射电子显微镜观察到膈肌自噬小泡增加了2.2倍（95%可信区间，1.8至2.5）（每组n = 5）。MV期间，仅膈肌的自噬体形成指数增加（1.5倍；95%可信区间，1.3至1.8；每组n = 8），而长期禁食诱导膈肌（2.5倍；95%可信区间，2.2至2.8）和肢体肌肉（4.1倍；95%可信区间，1.8至6.5）的自噬体形成。抗氧化剂N - 乙酰半胱氨酸在MV期间进一步增加了膈肌的自噬体形成（1.4倍；95%可信区间，1.2至1.5；每组n = 8），并预防了MV诱发的膈肌无力。用自噬诱导剂雷帕霉素治疗也在很大程度上预防了与MV相关的膈肌力量损失（每组n = 6）。
在这个VIDD模型中，MV诱导自噬，但自噬不是膈肌无力的原因。作者提出，自噬可能是一种有益的适应性反应，有可能用于VIDD的治疗。
