Novel Iron Prochelators for Protection Against Oxidative Stress in RPE Cells

描述（由申请人提供）：氧化应激与多种疾病有关，包括但不限于年龄相关性黄斑变性（AMD）、糖尿病、动脉粥样硬化、衰老和神经变性。氧化应激的生化标记，包括脂质过氧化、DNA碱基羟基化和蛋白质修饰，主要是由高活性羟基自由基（OH7）与氧的反应产生的，OH7本身是铁催化反应的产物。虽然铁是健康细胞必不可少的有益成分，但这种有害的反应性表明，细胞中的任何游离铁都会造成重大损害。因此，抑制金属促进的氧化应激是治疗许多疾病的一种有希望的策略，特别是那些正常金属离子稳态受损或记录异常金属积累的疾病，如AMD的情况。广泛的铁螯合可以防止氧化损伤，但如果代谢过程所需的铁被去除，也可能是有害的。我们正在设计只在需要时才有活性的螯合剂（促螯合剂）：它们选择性地隔离和灭活细胞中的氧化应激铁，从而限制这些细胞的氧化损伤。这些螯合剂是水杨醛异烟碱酰腙（SIH）的化学修饰，我们发现它能够保护培养的视网膜色素上皮细胞（RPE）免受各种损伤引起的死亡。我们建议在RPE细胞中测试几种修饰的SIH分子在细胞经历氧化应激时选择性减少不稳定铁池的能力，并确定螯合剂是否能提高细胞活力。初步结果表明，这些促因子在试管和RPE细胞中均被氧化应激激活，它们可以保护培养的RPE细胞免受氧化诱导的死亡。本提案的目标是确定具有最佳特性的促剂：最大的RPE保护和最小的毒性。这些研究将为今后在小鼠视网膜变性模型中进行促前体的试验奠定基础。希望这些研究能够为早期AMD患者提供一种新的预防药物。

DESCRIPTION (provided by applicant): Oxidative stress is implicated in a wide variety of diseases, including but not limited to age-related macular degeneration (AMD), diabetes, atherosclerosis, aging, and neurodegeneration. The biochemical markers of oxidative stress, including lipid peroxidation, DNA base hydroxylation, and protein modification, result primarily from reaction with the highly reactive hydroxyl radical, OH7, itself a product of iron-catalyzed reactions, with oxygen species. While iron is an essential and beneficial component of healthy cells, this deleterious reactivity suggests that any free iron in the cell will cause significant damage. Inhibiting metal-promoted oxidative stress is therefore a promising strategy for treating a number of diseases, especially those where normal metal ion homeostasis is impaired or where aberrant metal accumulation is documented, as is the case for AMD. Generalized iron chelation could protect against oxidative damage, but could also be detrimental if iron needed for metabolic processes is removed. We are designing chelating agents (prochelators) that are active only when needed: they selectively sequester and inactivate iron only in cells undergoing oxidative stress, thereby limiting oxidative damage in these cells. These chelators are chemical modifications of salicylaldehyde isonicotinoyl hydrazone (SIH), which we have found able to protect cultured retinal pigment epithelial cells (RPE) from death induced by a wide variety of insults. We propose herein to test in RPE cells the ability of several modified SIH molecules to decrease the labile iron pool selectively when cells are experiencing oxidative stress, and to determine whether the chelators increase cell viability. Preliminary results suggest that these prochelators are activated by oxidative stress both in the test tube and in RPE cells, and that they can protect cultured RPE cells from oxidant induced death. The goal of this proposal is to identify prochelators with the optimal characteristics: maximal RPE protection with minimal toxicity. These studies will lay the groundwork for future prochelator testing in mouse retinal degeneration models. It is hoped that these studies will lead to a new preventative agent for patients with early AMD.