Pieper Galen M, Roza Allan M, Adams Mark B, Hilton Gail, Johnson Mary, Felix Christopher C, Kampalath Bal, Darkes Marilyn, Wanggui Yangsheng, Cameron Beth, Fricker Simon P
Department of Surgery, Division of Transplant Surgery, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.
J Cardiovasc Pharmacol. 2002 Mar;39(3):441-8. doi: 10.1097/00005344-200203000-00016.
Nitric oxide (NO) derived from the up-regulation of inducible NO synthase (iNOS) is believed to play an important role in organ rejection. In experimental models of acute cardiac transplant rejection (i.e., without immunosuppression), treatment using NOS inhibitors to prevent acute rejection have yielded conflicting results. This is most likely due to potential inhibition of constitutive NOS. Accordingly, agents that trap NO directly may have some advantage. In the current study, we evaluated the actions of a ruthenium-based NO scavenger, AMD6221, to inhibit the nitrosylation of myocardial protein and to prolong cardiac allograft survival in a model of acute cardiac transplant rejection (without immunosuppression). In addition, we evaluated the efficacy of AMD6221 used in combination with low-dose cyclosporine (CsA) (i.e., a model of delayed graft rejection). Heterotopic abdominal cardiac transplantation was performed using rat strains with disparities at major and minor histocompatibility loci. Grafts were harvested on postoperative day 6 for histologic examination or analysis of myocardial protein nitrosylation using electron paramagnetic resonance (EPR) spectroscopy. Other animals were monitored twice daily to determine rejection times. Plasma was also taken at postoperative day 6 for determining the concentration of NO by-products (nitrate plus nitrite). Treatment with AMD6221 either prolonged graft survival and/or caused a marked decrease in myocardial nitrosylprotein formation as determined by EPR spectroscopy. In vivo scavenging of NO by AMD6221 was verified by high-performance liquid chromatography analysis of nitrosylated-drug in plasma samples. Low-dose CsA given alone or in combination with AMD6221 completely blocked formation of myocardial nitrosylprotein complexes. Whereas low-dose CsA alone prolonged graft survival, combination therapy with CsA plus AMD6221 produced a synergistic effect on graft survival. These studies indicate that treatment with a ruthenium-based NO scavenger, such as AMD6221, may be an effective regimen used alone or in combination with CsA to protect myocardial proteins from posttranscriptional modification and to prolong cardiac graft survival.
诱导型一氧化氮合酶（iNOS）上调产生的一氧化氮（NO）被认为在器官排斥中起重要作用。在急性心脏移植排斥的实验模型中（即不进行免疫抑制），使用一氧化氮合酶抑制剂预防急性排斥的治疗产生了相互矛盾的结果。这很可能是由于对组成型一氧化氮合酶的潜在抑制。因此，直接捕获NO的药物可能具有一些优势。在当前研究中，我们评估了一种基于钌的NO清除剂AMD6221在急性心脏移植排斥模型（不进行免疫抑制）中抑制心肌蛋白亚硝化和延长心脏同种异体移植存活时间的作用。此外，我们评估了AMD6221与低剂量环孢素（CsA）联合使用的疗效（即延迟移植排斥模型）。使用在主要和次要组织相容性位点存在差异的大鼠品系进行异位腹部心脏移植。在术后第6天收获移植物用于组织学检查或使用电子顺磁共振（EPR）光谱分析心肌蛋白亚硝化。每天对其他动物进行两次监测以确定排斥时间。术后第6天也采集血浆以测定NO副产物（硝酸盐加亚硝酸盐）的浓度。通过EPR光谱测定，AMD6221治疗要么延长了移植物存活时间和/或导致心肌亚硝基化蛋白形成显著减少。通过对血浆样品中亚硝基化药物的高效液相色谱分析验证了AMD6221在体内对NO的清除作用。单独给予低剂量CsA或与AMD6221联合使用完全阻断了心肌亚硝基化蛋白复合物的形成。虽然单独使用低剂量CsA可延长移植物存活时间，但CsA加AMD6221的联合治疗对移植物存活产生了协同作用。这些研究表明，使用基于钌的NO清除剂（如AMD6221）进行治疗可能是一种单独使用或与CsA联合使用的有效方案，以保护心肌蛋白免受转录后修饰并延长心脏移植物存活时间。
