Department of Histology and Embryology, School of Basic Medical Sciences, Capital Medical University, Beijing, China.
Department of Molecular Pharmacology, School of Pharmacy, Wenzhou Medical University, Wenzhou, China.
Nephrol Dial Transplant. 2017 Oct 1;32(10):1628-1636. doi: 10.1093/ndt/gfw469.
Epithelial-mesenchymal transition (EMT) plays a critical role in renal fibrosis. We hypothesize that mitochondrial DNA damage and DNA deletions caused by reactive oxygen species (ROS) during renal ischemia-reperfusion injury (IRI) might lead to EMT in renal fibrosis.
Rats were classified into seven groups: sham-operation, IRI, postconditioning (POC), I/R + apocynin, POC + apocynin, I/R + Mito-Tempol (Mito-T) and POC + Mito-T. These groups were monitored for up to 3 months. Serum creatinine, renal histopathology changes and mitochondrial oxidative stress were examined. We also treated NRK52E cells with 200 μM hydrogen peroxide to evaluate the effect of ROS on EMT development, and with 400 ng/mL ethidium bromide to assess the extent of mitochondrial DNA depletion during EMT.
Three months after IRI injury, the IRI group showed significant renal fibrosis, increased generation of ROS and higher mitochondrial DNA damage and DNA deletions. However, the severity of renal fibrosis and mitochondrial oxidative stress were markedly attenuated in the POC group. Studies on NRK52E cells showed that mitochondrial DNA damage triggered the development of EMT.
Mitochondrial DNA damage induced by elevated ROS production likely leads to EMT, and might further result in renal fibrosis. POC treatment might attenuate the degree of renal fibrosis by protecting mitochondria from oxidative stress-induced mitochondrial DNA damage.
上皮间质转化（EMT）在肾纤维化中起着关键作用。我们假设在肾缺血再灌注损伤（IRI）过程中活性氧（ROS）引起的线粒体 DNA 损伤和 DNA 缺失可能导致肾纤维化中的 EMT。
大鼠分为 7 组：假手术组、IRI 组、预处理组（POC）、IRI+apocynin 组、POC+apocynin 组、IRI+Mito-Tempol（Mito-T）组和 POC+Mito-T 组。这些组被监测了长达 3 个月。检测血清肌酐、肾组织病理学变化和线粒体氧化应激。我们还用 200μM 过氧化氢处理 NRK52E 细胞，以评估 ROS 对 EMT 发展的影响，并用 400ng/ml 溴化乙锭评估 EMT 期间线粒体 DNA 耗竭的程度。
在 IRI 损伤后 3 个月，IRI 组表现出明显的肾纤维化、ROS 生成增加以及更高的线粒体 DNA 损伤和 DNA 缺失。然而，在 POC 组，肾纤维化和线粒体氧化应激的严重程度明显减轻。对 NRK52E 细胞的研究表明，线粒体 DNA 损伤引发了 EMT 的发生。
ROS 产生增加引起的线粒体 DNA 损伤可能导致 EMT，并可能进一步导致肾纤维化。POC 治疗可能通过保护线粒体免受氧化应激诱导的线粒体 DNA 损伤来减轻肾纤维化的程度。
