Oxidants, Mitochondria,and Renal Ischemia/Reperfusion

这项建议解决了移植生物学中的一个关键问题，通过关注移植前供体采集和/或保存技术中肾脏缺血性损伤后的早期损伤(30分钟至2天)。线粒体功能障碍发生在缺血/再灌注(I/R)期间，并可能增加线粒体内活性氧(ROS)的产生。这项研究扩展和补充了PI在体外和体内的观察结果，即在肾移植过程中，线粒体中的主要抗氧化剂锰超氧化物歧化酶(MnSOD)被酪氨酸硝化和失活。MnSOD活性丧失的最终结果是对敏感的电子传递系统造成损害，并伴随着ROS产生的增加，从而放大进一步的细胞损伤。在体大鼠肾脏I/R模型的初步研究表明，MnSOD在肾脏I/R损伤过程中早期被酪氨酸硝化。这些数据与I/R期间ROS介导的损伤增加是一致的，提示MnSOD是一个可能导致氧化损伤并使肾脏更容易受到后续损伤的早期靶点。我们假设肾脏保存和I/R通过MnSOD蛋白的改变导致氧化应激增加，而MnSOD蛋白在移植前导致肾脏和线粒体损伤。这项建议的目的是确定体内保存和I/R后氧化剂产生的增加在导致肾功能障碍的早期事件中的作用。显然，肾脏损伤发生在I/R期间，因此，在冷和/或热缺血期间限制肾脏损伤的程度将极大地改善肾移植后的移植肾功能。这些研究的一个基本主题是将器官保存和I/R期间增加的ROS产生与MnSOD功能的丧失联系起来。这些信息将有助于确定可能的治疗干预措施，以改进目前的肾脏保存和移植技术。

This proposal addresses a critical issue in transplantation biology by focusing on the early injury (30 minutes to 2 days) following ischemic damage to the kidney during donor harvesting and/or preservation techniques, prior to transplantation. Mitochondrial dysfunction occurs during ischemia/reperfusion (I/R) episodes, and likely increases intra- mitochondrial reactive oxygen species (ROS) production. This study both extends and compliments the PI's in vitro and in vivo observations that during renal transplantation manganese superoxide dismutase (MnSOD), the major antioxidant in the mitochondria, is tyrosine nitrated and inactivated. The net result of loss of MnSOD activity is damage to sensitive electron transport systems and an accompanying increase in ROS production, thus amplifying further cellular injury. Preliminary studies using an in vivo rat kidney I/R model suggest that MnSOD is tyrosine nitrated early during renal I/R injury. These data are consistent with increased ROS-mediated injury during I/R and suggest that MnSOD is an early target that may result in oxidative injury and predispose the kidney to subsequent injury. We hypothesize that renal preservation and I/R leads to increased oxidative stress via alterations in MnSOD protein, which contributes to renal and mitochondrial injury prior to transplantation. The aims of this proposal are to determine the role that increased oxidant production has on the early events leading to renal dysfunction following preservation and I/R in vivo. Clearly, kidney damage occurs during I/R, therefore, strategies to limit the extent of renal damage during the cold and/or warm ischemic periods would most certainly improve graft function following renal transplantation. An underlying theme of these studies is to relate the increased ROS production to loss of MnSOD function during organ preservation and I/R. This information will be helpful in determining possible therapeutic interventions for improving current techniques in renal preservation and transplantation.