Translational Research Program, Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research, Baltimore, Maryland.
The Department of Physiology and Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, Maryland.
Shock. 2022 Apr 1;57(4):553-564. doi: 10.1097/SHK.0000000000001858.
Sepsis-induced cardiomyopathy (SIC) is a major contributing factor for morbidity and mortality in sepsis. Accumulative evidence has suggested that cardiac mitochondrial oxidative phosphorylation is attenuated in sepsis, but the underlying molecular mechanisms remain incompletely understood.
Adult male mice of 9 to 12 weeks old were subjected to sham or cecal ligation and puncture procedure. Echocardiography in vivo and Langendorff-perfused hearts were used to assess cardiac function 24 h after the procedures. Unbiased proteomics analysis was performed to profile mitochondrial proteins in the hearts of both sham and SIC mice. Seahorse respirator technology was used to evaluate oxygen consumption in purified mitochondria.
Of the 665 mitochondrial proteins identified in the proteomics assay, 35 were altered in septic mice. The mitochondrial remodeling involved various energy metabolism pathways including subunits of the electron transport chain, fatty acid catabolism, and carbohydrate oxidative metabolism. We also identified a significant increase of pyruvate dehydrogenase (PDH) kinase 4 (PDK4) and inhibition of PDH activity in septic hearts. Furthermore, compared to sham mice, mitochondrial oxygen consumption of septic mice was significantly reduced when pyruvate was provided as a substrate. However, it was unchanged when PDH was bypassed by directly supplying the Complex I substrate NADH, or by using the Complex II substrate succinate, or using Complex IV substrate, or by providing the beta-oxidation substrate palmitoylcarnitine, neither of which require PDH for mitochondrial oxygen consumption.
These data demonstrate a broad mitochondrial protein remodeling, PDH inactivation and impaired pyruvate-fueled oxidative phosphorylation during SIC, and provide a molecular framework for further exploration.
脓毒症性心肌病（SIC）是脓毒症患者发病率和死亡率的主要因素。越来越多的证据表明，脓毒症时心脏线粒体氧化磷酸化功能减弱，但潜在的分子机制尚不完全清楚。
将 9 至 12 周龄的成年雄性小鼠进行假手术或盲肠结扎和穿刺手术。术后 24 小时，通过体内超声心动图和 Langendorff 灌流心脏评估心功能。使用无偏蛋白质组学分析方法对假手术和 SIC 小鼠心脏的线粒体蛋白进行分析。使用 Seahorse 呼吸仪技术评估纯化线粒体中的耗氧量。
在蛋白质组学分析中鉴定出 665 种线粒体蛋白，其中 35 种在脓毒症小鼠中发生改变。线粒体重构涉及多种能量代谢途径，包括电子传递链亚基、脂肪酸分解代谢和碳水化合物氧化代谢。我们还发现脓毒症心脏中丙酮酸脱氢酶（PDH）激酶 4（PDK4）显著增加，PDH 活性受到抑制。与假手术小鼠相比，当提供丙酮酸作为底物时，脓毒症小鼠的线粒体耗氧量明显降低；然而，当通过直接提供复合物 I 底物 NADH、复合物 II 底物琥珀酸、复合物 IV 底物或提供β-氧化底物肉碱绕过 PDH 时，线粒体耗氧量没有变化，这些都不需要 PDH 进行线粒体氧化磷酸化。
这些数据表明 SIC 期间存在广泛的线粒体蛋白重构、PDH 失活和丙酮酸供能的氧化磷酸化受损，为进一步研究提供了分子框架。
