Department of Nephro-urology, Nagoya City University Graduate School of Medical Sciences, Nagoya 467-8601, Japan.
Free Radic Biol Med. 2012 Apr 1;52(7):1207-17. doi: 10.1016/j.freeradbiomed.2012.01.005. Epub 2012 Jan 18.
Renal tubular cell injury induced by oxidative stress via mitochondrial collapse is thought to be the initial process of renal calcium crystallization. Mitochondrial collapse is generally caused by mitochondrial permeability transition pore (mPTP) opening, which can be blocked by cyclosporine A (CsA). Definitive evidence for the involvement of mPTP opening in the initial process of renal calcium crystallization, however, is lacking. In this study, we examined the physiological role of mPTP opening in renal calcium crystallization in vitro and in vivo. In the in vitro study, cultured renal tubular cells were exposed to calcium oxalate monohydrate (COM) crystals and treated with CsA (2 μM). COM crystals induced depolarization of the mitochondrial membrane potential and generated oxidative stress as evaluated by Cu-Zn SOD and 4-HNE. Furthermore, the expression of cytochrome c and cleaved caspase 3 was increased and these effects were prevented by CsA. In the in vivo study, Sprague-Dawley rats were administered 1% ethylene glycol (EG) to generate a rat kidney stone model and then treated with CsA (2.5, 5.0, and 10.0 mg/kg/day) for 14 days. EG administration induced renal calcium crystallization, which was prevented by CsA. Mitochondrial collapse was demonstrated by transmission electron microscopy, and oxidative stress was evaluated by measuring Cu-Zn SOD, MDA, and 8-OHdG generated by EG administration, all of which were prevented by CsA. Collectively, our results provide compelling evidence for a role of mPTP opening and its associated mitochondrial collapse, oxidative stress, and activation of the apoptotic pathway in the initial process of renal calcium crystallization.
氧化应激诱导的肾小管细胞损伤通过线粒体崩溃被认为是肾脏钙结晶的初始过程。线粒体崩溃通常是由线粒体通透性转换孔（mPTP）开放引起的，可以被环孢素 A（CsA）阻断。然而，mPTP 开放在肾脏钙结晶初始过程中的参与还缺乏明确的证据。在这项研究中，我们在体外和体内研究了 mPTP 开放在肾脏钙结晶中的生理作用。在体外研究中，培养的肾小管细胞暴露于草酸钙一水合物（COM）晶体，并给予 CsA（2 μM）处理。COM 晶体诱导线粒体膜电位去极化，并产生氧化应激，如 Cu-Zn SOD 和 4-HNE 评估的那样。此外，细胞色素 c 和裂解的 caspase 3 的表达增加，这些作用被 CsA 预防。在体内研究中，给予 Sprague-Dawley 大鼠 1%乙二醇（EG）以生成大鼠肾结石模型，然后给予 CsA（2.5、5.0 和 10.0 mg/kg/天）治疗 14 天。EG 给药诱导肾脏钙结晶，CsA 可预防其发生。通过透射电子显微镜证实了线粒体崩溃，通过测量 EG 给药引起的 Cu-Zn SOD、MDA 和 8-OHdG 来评估氧化应激，所有这些都被 CsA 预防。总之，我们的结果为 mPTP 开放及其相关的线粒体崩溃、氧化应激和凋亡途径的激活在肾脏钙结晶的初始过程中的作用提供了有力的证据。
