Turman M A, Bates C M
Department of Pediatrics, Ohio State University, Columbus 43205, USA.
Ren Fail. 1997 Jan;19(1):47-60. doi: 10.3109/08860229709026259.
In animals models, exposure of the brain, heart, or kidneys to sublethal ischemia induces tolerance for subsequent ischemia. However, the ability of human renal cells to undergo hypoxic preconditioning has not been evaluated. In addition, it is unclear if renal ischemic preconditioning induces resistance at the cellular level, or if preconditioning is a result of altered postischemic hemodynamics or the azotemic environment. In this study, we tested the ability of cultured human proximal tubular epithelial cells (PTEC) to undergo hypoxic preconditioning at the cellular level. Hypoxia was induced by incubating cells in an anaerobic incubator in glucose-free buffer (combined oxygen-glucose deprivation; COGD). Cell injury was assessed by lactate dehydrogenase (LDH) efflux, release of arachidonic acid metabolites, and light microscopy. PTEC preconditioned with 12 h of COGD and a 24-h recovery period had less LDH efflux than control PTEC after subsequent exposure to 20 h of COGD (15.0 +/- 2.5% vs. 44.0 +/- 3.4%, p < 0.05). Preconditioned PTEC also retained relatively normal morphology and had less release of arachidonic acid metabolites than control PTEC. Because renal ischemia is characterized predominately by tubular injury with relative sparing of the glomerulus, we determined if PTEC are more susceptible to hypoxic injury than glomerular cells. For further comparison, we also assessed the susceptibility to hypoxia of the porcine tubular epithelial cell line LLC-PK1. After exposure to 18 h of COGD, LDH efflux from PTEC (25.5 +/- 3.3%, mean +/- SEM) was lower than from LLC-PK1 cells (47.6 +/- 4.0%; p < 0.01), but not mesangial cells (22.7 +/- 5.0%) or glomerular endothelial cells (38.2 +/- 6.2%). In conclusion, we have demonstrated that cultured PTEC are as resistant to hypoxic injury as glomerular cells, and that PTEC attain cytoresistance after hypoxic preconditioning. Characterization of the molecular changes that occur in human PTEC after hypoxic preconditioning may reveal innate survival mechanisms that can be manipulated to promote protection from renal ischemia in patients.
在动物模型中，将脑、心脏或肾脏暴露于亚致死性缺血可诱导对后续缺血的耐受性。然而，人类肾细胞进行缺氧预处理的能力尚未得到评估。此外，尚不清楚肾缺血预处理是否在细胞水平诱导抗性，或者预处理是否是缺血后血流动力学改变或氮质血症环境的结果。在本研究中，我们在细胞水平测试了培养的人近端肾小管上皮细胞（PTEC）进行缺氧预处理的能力。通过在无葡萄糖缓冲液的厌氧培养箱中孵育细胞（联合氧-葡萄糖剥夺；COGD）来诱导缺氧。通过乳酸脱氢酶（LDH）外流、花生四烯酸代谢产物的释放和光学显微镜评估细胞损伤。经过12小时COGD预处理和24小时恢复期的PTEC在随后暴露于20小时COGD后，其LDH外流比对照PTEC少（15.0±2.5%对44.0±3.4%，p<0.05）。预处理的PTEC也保持相对正常的形态，并且花生四烯酸代谢产物的释放比对照PTEC少。由于肾缺血主要以肾小管损伤为特征，而肾小球相对 spared，我们确定PTEC是否比肾小球细胞更容易受到缺氧损伤。为了进一步比较，我们还评估了猪肾小管上皮细胞系LLC-PK1对缺氧的敏感性。暴露于18小时COGD后，PTEC的LDH外流（25.5±3.3%，平均值±标准误）低于LLC-PK1细胞（47.6±4.0%；p<0.01），但低于系膜细胞（22.7±5.0%）或肾小球内皮细胞（38.2±6.2%）。总之，我们已经证明培养的PTEC对缺氧损伤的抗性与肾小球细胞相同，并且PTEC在缺氧预处理后获得细胞抗性。对缺氧预处理后人PTEC中发生的分子变化进行表征可能揭示先天的存活机制，这些机制可被操纵以促进对患者肾缺血的保护。 （注：原文中“sparing”可能有误，推测为“spared”，翻译为“ spared”即“相对 spared”，但此词在医学语境中不太常见，可能影响译文准确性，需结合更详细的专业知识进一步确认。）
