Oxidants, Mitochondria,and Renal Ischemia/Reperfusion

该提案通过关注移植前供体收获和/或保存技术期间肾脏缺血损伤后的早期损伤（30分钟至2天），解决了移植生物学中的一个关键问题。线粒体功能障碍发生在缺血/再灌注（I/R）发作期间，并可能增加线粒体内活性氧（ROS）的产生。该研究扩展并补充了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）被酪氨酸硝化并失活。MnSOD活性丧失的净结果是对敏感的电子传递系统的损害，并伴随ROS产生的增加，从而进一步放大细胞损伤。在体内大鼠肾I/R模型的初步研究表明，MnSOD在肾I/R损伤早期被酪氨酸硝化。这些数据与I/R期间ros介导的损伤增加一致，表明MnSOD是一个早期靶点，可能导致氧化损伤，并使肾脏易受后续损伤。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，这有助于移植前肾脏和线粒体损伤。本提案的目的是确定增加的氧化剂产生在体内保存和I/R后导致肾功能障碍的早期事件中的作用。显然，肾损伤发生在I/R期间，因此，在寒冷和/或温暖缺血期间限制肾损伤程度的策略肯定会改善肾移植后的移植物功能。这些研究的一个潜在主题是在器官保存和I/R过程中，ROS产生的增加与MnSOD功能的丧失有关。这些信息将有助于确定可能的治疗干预措施，以改进当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.