Section of Forensic Medicine, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University.
Hepatol Res. 2013 May;43(5):526-34. doi: 10.1111/j.1872-034X.2012.01084.x. Epub 2012 Sep 13.
The purpose of the present study was to identify molecular markers of hepatic damage during lipopolysaccharide (LPS) treatment.
LPS (15 mg/kg of bodyweight) or vehicle was injected i.p. into 5-week-old male Sprague-Dawley rats. Proteins were extracted from the liver and were electrophoresed to examine the changes in the protein compositions during LPS treatment. Using a proteomic approach, major LPS-responsible protein in the liver was determined.
A massive reduction in the levels of carbamoyl phosphate synthase-1 (CPS1), one of the most abundant proteins in liver mitochondria, was revealed during LPS administration. Electron microscopic and immunofluorescence analyses revealed large vacuoles, which were often localized in the vicinity of mitochondria, in the LPS-treated rat liver. Furthermore, we found that CPS1 is released into the circulation prior to liver damage marker alanine aminotransferase, indicating the active extrusion of CPS1 during LPS administration. Another liver mitochondrial protein, ornithine transcarbamylase, is also released into the circulation, implicating active extrusion of mitochondrial proteins. These phenomena are accelerated by a heme oxygenase inducer cobalt protoporphyrin whilst suppressed by a lysosome inhibitor chloroquine.
Plasma CPS1 should be a possible marker of septic liver damage and may be involved in systemic responses elicited by septic shock.
本研究旨在确定脂多糖（LPS）治疗过程中肝损伤的分子标志物。
将 LPS（15mg/kg 体重）或载体通过腹腔注射到 5 周龄雄性 Sprague-Dawley 大鼠体内。从肝脏中提取蛋白质，并进行电泳，以检查 LPS 处理过程中蛋白质组成的变化。采用蛋白质组学方法，确定肝脏中主要的 LPS 反应蛋白。
在 LPS 给药期间，发现肝脏线粒体中含量最丰富的蛋白质之一的氨基甲酰磷酸合成酶-1（CPS1）水平大量降低。电子显微镜和免疫荧光分析显示，在 LPS 处理的大鼠肝脏中存在大的空泡，这些空泡通常位于线粒体附近。此外，我们发现 CPS1 在肝损伤标志物丙氨酸氨基转移酶之前释放到循环中，表明在 LPS 给药期间 CPS1 的主动外排。另一种肝脏线粒体蛋白鸟氨酸转氨甲酰酶也释放到循环中，表明线粒体蛋白的主动外排。血红素加氧酶诱导剂钴原卟啉加速了这些现象，而溶酶体抑制剂氯喹则抑制了这些现象。
血浆 CPS1 可能是脓毒症肝损伤的一个潜在标志物，可能参与脓毒性休克引起的全身反应。
