Division of Cardiovascular Disease, Department of Medicine, University of Alabama at Birmingham (UAB) Cardiovascular Institute, University of Alabama at Birmingham, Birmingham, Ala.
Department of Pathology and Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, Ala.
J Thorac Cardiovasc Surg. 2022 Dec;164(6):e289-e308. doi: 10.1016/j.jtcvs.2020.11.102. Epub 2020 Dec 3.
Hemolysis, characterized by formation of free hemoglobin (Hb), occurs in patients undergoing cardiopulmonary bypass (CPB). However, there is no study of the dynamic changes in red blood cell (RBC)-derived exosomes (Exos) released during CPB, nor whether these particles mediate acute kidney injury (AKI).
This study is a comprehensive time-course analysis, at baseline, 30 minutes, to 24 hours post-crossclamp release (XCR) to determine (1) Exos Hb content; (2) free Hb/heme, haptoglobin, hemopexin; and (3) urinary markers of AKI over the same time period. In addition, we developed a model system in Sprague-Dawley rats to test for AKI after intravenous injection of Exos Hb released during CPB.
In 30 patients undergoing CPB, there is a significant increase in plasma Hb-positive Exos but not microvesicles 30 minutes post-XCR versus other time points, with a simultaneous decrease in the haptoglobin/Hb ratio. These changes presage a significant increase in urine neutrophil gelatinase-associated lipocalin and kidney injury molecule-1 at 24 hours. Intravenous injection of plasma Exos (10 particles obtained 30 minutes post-XCR) into rats causes AKI at 72 hours, manifested by multifocal degeneration of proximal tubular epithelium. At 21 days, there is persistent tubular injury and interstitial fibrosis. Intravenous injection of Exos from 35-day-old stored RBCs into rats results in glomerular-tubular injury, increased kidney ferritin and hemoxygenase-1 expression, and significant elevation of kidney injury molecule-1 and proteinuria at 72 hours.
These combined studies raise the potential for RBC-derived Exos, released during CPB, to target the kidney and mediate AKI.
体外循环 (CPB) 过程中会发生溶血，其特征是游离血红蛋白 (Hb) 的形成。然而，目前尚缺乏对 CPB 过程中释放的红细胞 (RBC) 衍生外泌体 (Exos) 动态变化的研究，也不清楚这些颗粒是否介导急性肾损伤 (AKI)。
本研究是一项全面的时间过程分析，在基线、CPB 夹闭后 30 分钟至 24 小时，确定 (1) Exos Hb 含量；(2) 同一时间内游离 Hb/血红素、触珠蛋白、血红素结合蛋白；以及 (3) AKI 的尿标志物。此外，我们在 Sprague-Dawley 大鼠中建立了一个模型系统，以测试 CPB 期间释放的 Exos Hb 静脉注射后是否会引起 AKI。
在 30 例接受 CPB 的患者中，CPB 夹闭后 30 分钟血浆 Hb 阳性 Exos 显著增加，但与其他时间点相比无微泡，同时触珠蛋白/Hb 比值降低。这些变化预示着 24 小时时尿液中性粒细胞明胶酶相关脂质运载蛋白和肾损伤分子-1 的显著增加。静脉注射 CPB 夹闭后 30 分钟获得的 10 个 Exos (10 个颗粒) 可导致大鼠在 72 小时发生 AKI，表现为近端肾小管上皮的多灶性变性。21 天时，存在持续的肾小管损伤和间质纤维化。静脉注射 35 天龄储存 RBC 的 Exos 会导致大鼠肾小球-肾小管损伤、增加肾脏铁蛋白和血红素加氧酶-1 的表达，并在 72 小时时显著升高肾损伤分子-1 和蛋白尿。
这些综合研究提出了 CPB 期间释放的 RBC 衍生 Exos 可能靶向肾脏并介导 AKI 的可能性。
