Emlet David R, Pastor-Soler Nuria, Marciszyn Allison, Wen Xiaoyan, Gomez Hernando, Humphries William H, Morrisroe Seth, Volpe Jacob K, Kellum John A
Center for Critical Care Nephrology, Department of Critical Care Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania.
Renal Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania; and.
Am J Physiol Renal Physiol. 2017 Feb 1;312(2):F284-F296. doi: 10.1152/ajprenal.00271.2016. Epub 2016 Dec 21.
We have characterized the expression and secretion of the acute kidney injury (AKI) biomarkers insulin-like growth factor binding protein 7 (IGFBP7) and tissue inhibitor of metalloproteinases-2 (TIMP-2) in human kidney epithelial cells in primary cell culture and tissue. We established cell culture model systems of primary kidney cells of proximal and distal tubule origin and observed that both proteins are indeed expressed and secreted in both tubule cell types in vitro. However, TIMP-2 is both expressed and secreted preferentially by cells of distal tubule origin, while IGFBP7 is equally expressed across tubule cell types yet preferentially secreted by cells of proximal tubule origin. In human kidney tissue, strong staining of IGFBP7 was seen in the luminal brush-border region of a subset of proximal tubule cells, and TIMP-2 stained intracellularly in distal tubules. Additionally, while some tubular colocalization of both biomarkers was identified with the injury markers kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin, both biomarkers could also be seen alone, suggesting the possibility for differential mechanistic and/or temporal profiles of regulation of these early AKI biomarkers from known markers of injury. Last, an in vitro model of ischemia-reperfusion demonstrated enhancement of secretion of both markers early after reperfusion. This work provides a rationale for further investigation of these markers for their potential role in the pathogenesis of acute kidney injury.
我们已经在原代细胞培养和组织中,对急性肾损伤(AKI)生物标志物胰岛素样生长因子结合蛋白7(IGFBP7)和金属蛋白酶组织抑制剂-2(TIMP-2)在人肾上皮细胞中的表达和分泌进行了表征。我们建立了近端和远端肾小管来源的原代肾细胞的细胞培养模型系统,并观察到这两种蛋白在体外的两种肾小管细胞类型中均有表达和分泌。然而,TIMP-2在远端肾小管来源的细胞中优先表达和分泌,而IGFBP7在各肾小管细胞类型中表达相同,但在近端肾小管来源的细胞中优先分泌。在人肾组织中,在一部分近端肾小管细胞的管腔刷状缘区域可见IGFBP7的强染色,而TIMP-2在远端肾小管细胞内染色。此外,虽然这两种生物标志物与损伤标志物肾损伤分子-1和中性粒细胞明胶酶相关脂质运载蛋白存在一些肾小管共定位,但这两种生物标志物也可单独见到,这表明这些早期AKI生物标志物与已知损伤标志物在调控机制和/或时间模式上可能存在差异。最后,缺血再灌注的体外模型显示,再灌注后早期这两种标志物的分泌均增强。这项工作为进一步研究这些标志物在急性肾损伤发病机制中的潜在作用提供了理论依据。