Department of Physiology and Cellular Biophysics, Clyde and Helen Wu Center for Molecular Cardiology Columbia University College of Physicians and Surgeons, New York, USA.
PhyMedExp, Montpellier University, INSERM, CNRS, CHRU Montpellier, 34295, Montpellier, France.
Free Radic Biol Med. 2020 Jan;146:383-391. doi: 10.1016/j.freeradbiomed.2019.11.019. Epub 2019 Nov 19.
Ventilator-induced diaphragm dysfunction (VIDD) increases morbidity and mortality in critical care patients. Although VIDD has been associated with mitochondrial oxidative stress and calcium homeostasis impairment, the underling mechanisms are still unknown. We hypothesized that diaphragmatic mitochondrial oxidative stress causes remodeling of the ryanodine receptor (RyR1)/calcium release channel, contributing to sarcoplasmic reticulum (SR) Ca leak, proteolysis and VIDD.
In mice diaphragms mechanically ventilated for short (6 h) and long (12 h) period, we assessed mitochondrial ROS production, mitochondrial aconitase activity as a marker of mitochondrial oxidative stress, RyR1 remodeling and function, Ca dependent proteolysis, TGFβ1 and STAT3 pathway, muscle fibers cross-sectional area, and diaphragm specific force production, with or without the mitochondrial targeted anti-oxidant peptide d-Arg-2', 6'-dimethyltyrosine-Lys-Phe-NH (SS31).
6 h of mechanical ventilation (MV) resulted in increased mitochondrial ROS production, reduction of mitochondrial aconitase activity, increased oxidation, S-nitrosylation, S-glutathionylation and Ser-2844 phosphorylation of RyR1, depletion of stabilizing subunit calstabin1 from RyR1, increased SR Ca leak. Preventing mROS production by SS31 treatment does not affect the TGFβ1 and STAT3 activation, which suggests that mitochondrial oxidative stress is a downstream pathway to TGFβ1 and STAT3, early involved in VIDD. This is further supported by the fact that SS-31 rescue all the other described cellular events and diaphragm contractile dysfunction induced by MV, while SS20, an analog of SS31 lacking antioxidant properties, failed to prevent these cellular events and the contractile dysfunction. Similar results were found in ventilated for 12 h. Moreover, SS31 treatment prevented calpain1 activity and diaphragm atrophy observed after 12 h of MV. This study emphasizes that mitochondrial oxidative stress during 6 h-MV contributes to SR Ca leak via RyR1 remodeling, and diaphragm weakness, while longer periods of MV (12 h) were also associated with increased Ca-dependent proteolysis and diaphragm atrophy.
呼吸机引起的膈肌功能障碍（VIDD）增加了重症监护患者的发病率和死亡率。虽然 VIDD 与线粒体氧化应激和钙稳态损伤有关，但潜在机制尚不清楚。我们假设膈肌线粒体氧化应激导致肌浆网（SR）钙泄漏、蛋白水解和 VIDD 的ryanodine 受体（RyR1）/钙释放通道重构。
在短时间（6 小时）和长时间（12 小时）机械通气的小鼠膈肌中，我们评估了线粒体 ROS 产生、作为线粒体氧化应激标志物的线粒体顺乌头酸酶活性、RyR1 重构和功能、Ca 依赖性蛋白水解、TGFβ1 和 STAT3 途径、肌纤维横截面积以及有或没有线粒体靶向抗氧化肽 d-Arg-2'，6'-二甲基酪氨酸-Lys-Phe-NH（SS31）时的膈肌特异性力产生。
6 小时机械通气（MV）导致线粒体 ROS 产生增加，线粒体顺乌头酸酶活性降低，RyR1 氧化、S-亚硝基化、S-谷胱甘肽化和 Ser-2844 磷酸化增加，RyR1 稳定亚基 calstabin1 耗竭，SR Ca 泄漏增加。SS31 治疗抑制 mROS 产生不影响 TGFβ1 和 STAT3 的激活，这表明线粒体氧化应激是 TGFβ1 和 STAT3 的下游途径，早期参与 VIDD。这进一步得到了以下事实的支持：SS-31 挽救了 MV 引起的所有其他描述的细胞事件和膈肌收缩功能障碍，而缺乏抗氧化特性的 SS20 类似物则不能防止这些细胞事件和收缩功能障碍。在通气 12 小时时也发现了类似的结果。此外，SS31 治疗可防止 MV 12 小时后观察到的钙蛋白酶 1 活性和膈肌萎缩。这项研究强调，6 小时 MV 期间的线粒体氧化应激通过 RyR1 重构导致 SR Ca 泄漏和膈肌无力，而较长时间的 MV（12 小时）也与增加的 Ca 依赖性蛋白水解和膈肌萎缩有关。
