Division of Internal Medicine, University of Zürich, Zürich, Switzerland.
Institute of Anesthesiology, University of Zürich, Zürich, Switzerland.
Cell Death Dis. 2016 Jan 21;7(1):e2064. doi: 10.1038/cddis.2015.392.
Intravascular hemolysis can result in hemoglobinuria with acute kidney injury. In this study we systematically explored two in vivo animal models and a related cell culture system to identify hemoglobinuria-triggered damage pathways. In models of stored blood transfusion and hemoglobin (Hb) exposure in guinea pigs and beagle dogs we found that hemoglobinuria led to intrarenal conversion of ferrous Hb(Fe(2+)) to ferric Hb(Fe(3+)), accumulation of free heme and Hb-cross-linking products, enhanced 4-hydroxynonenal reactivity in renal tissue, and acute tubule injury. These changes were associated in guinea pigs with activation of a renal cortex gene expression signature indicative of oxidative stress and activation of the unfolded protein response (UPR). Tubule cells of hemolytic animals demonstrated enhanced protein expression of heme oxygenase and heat shock protein and enhanced expression of acute kidney injury-related neutrophil gelatinase-associated lipocalin. These adverse changes were completely prevented by haptoglobin treatment. The in vivo findings were extrapolated to a MS-based proteome analysis of SILAC-labeled renal epithelial cells that were exposed to free heme within a concentration range estimate of renal tubule heme exposure. These experiments confirmed that free heme is a likely trigger of tubule barrier deregulation and oxidative cell damage and reinforced the hypothesis that uncontrolled free heme could trigger the UPR as an important pathway of renal injury during hemoglobinuria.
血管内溶血可导致血红蛋白尿和急性肾损伤。在这项研究中，我们系统地探索了两种体内动物模型和相关的细胞培养系统，以确定血红蛋白尿触发的损伤途径。在豚鼠和比格犬储存血输血和血红蛋白（Hb）暴露模型中，我们发现血红蛋白尿导致亚铁血红蛋白（Fe(2+)）在肾内转化为高铁血红蛋白（Fe(3+)），游离血红素和 Hb 交联产物积累，肾组织中 4-羟基壬烯醛反应性增强，以及急性肾小管损伤。这些变化与豚鼠肾皮质基因表达谱的激活有关，该基因表达谱表明存在氧化应激和未折叠蛋白反应（UPR）的激活。溶血性动物的肾小管细胞表现出血红素加氧酶和热休克蛋白的蛋白表达增强，以及急性肾损伤相关的中性粒细胞明胶酶相关脂质运载蛋白的表达增强。这些不利变化完全可以通过触珠蛋白治疗来预防。这些体内发现被外推到基于 MS 的蛋白质组分析，即用 SILAC 标记的肾上皮细胞在游离血红素存在的浓度范围内进行暴露，估计是肾小管血红素暴露的浓度范围。这些实验证实，游离血红素可能是肾小管屏障失调和氧化细胞损伤的触发因素，并强化了这样的假说，即不受控制的游离血红素可能会引发 UPR，作为血红蛋白尿期间肾损伤的重要途径。
