Protective Efficacy of Mg-Supplementation Against NRTI-induced Cardiac Toxicity

描述（由申请人提供）：齐多夫定（AZT）对HIV患者的心脏毒性已被充分记录，但补充镁（Mg）的潜在有益作用从未被探索过。AZT毒性与氧化应激增加有关，这可能是由异常铁状态介导的。由于其他临床使用的核苷类逆转录酶抑制剂（NRTI）药物在结构上与AZT相似，它们与内源性铁的潜在相互作用可能代表了氧化毒性的常见机制。我们的体外研究表明，AZT协同铁在引起内皮细胞毒性和超水平的细胞外镁细胞保护。该提案将探索膳食补充氧化镁（无机）或葡萄糖酸镁（有机盐）是否会减轻体内慢性NRTI诱导的全身性炎症和心脏损伤，以及是否可以使用NRTI处理的体外模型揭示与镁补充剂相关的保护机制。具体目标是：（1）确定补充无机和有机镁盐对AZT的不同保护作用（和其他NRTI）介导的膜和内皮细胞氧化损伤;（2）评估膳食补充镁盐是否（氧化镁和葡萄糖酸镁：比正常高3倍和6倍）减弱慢性AZT诱导的心血管炎症、氧化应激和中性粒细胞活化;和（3）确定Mg补充是否减弱AZT增强的离体心肌对施加的缺血/再灌注（I/R）应激的敏感性。我们将采用免疫组织化学和病理学技术来定位炎性细胞因子和白色血细胞浸润。将通过组织/血液谷胱甘肽状态、铁状态和脂质过氧化产物（F2-异前列烷、共轭二烯）的变化，以生化方式确定体内氧化应激。对灌注心脏I/R-应激的耐受性的变化将通过自由基产生（ESR自旋捕获）以及氧化组织损伤标志物和功能恢复的改变来确定。这项拟议的探索性工作可能揭示了镁补充剂作为一种有效且相对便宜的辅助治疗方法的潜在用途，以减轻NRTI相关的心血管毒性。

DESCRIPTION (provided by applicant): Zidovudine (AZT) cardiotoxicity in HIV patients has been well documented, but the potential beneficial effect of magnesium (Mg)-supplementation has never be explored. AZT toxicity is linked to increased oxidative stress which may be mediated by abnormal iron status. Since other clinically used nucleoside reverse transcriptase inhibitor (NRTI) drugs are structurally similar to AZT, their potential interaction with endogenous iron may represent a common mechanism of oxidative toxicity. Our in vitro studies suggest that AZT synergizes with iron in causing endothelial cytotoxicity and that supra levels of extracellular magnesium are cytoprotective. This proposal will explore whether dietary supplementation of either Mg oxide (inorganic) or Mg gluconate (an organic salt) will attenuate chronic NRTI-induced systemic inflammation and cardiac injury n vivo, and if the protective mechanism(s) associated with the Mg supplements can be revealed using NRTI- treated in vitro models. The specific aims are: (1) Determine the differential protective effects of upplemental inorganic and organic Mg-salts against AZT (and other NRTIs)-mediated membrane and endothelial cell oxidative injury; (2) Assess if dietary supplementation of Mg-salts (Mg oxide and Mg- gluconate: 3 and 6- fold higher than normal) in the rat attenuates chronic AZT-induced cardiovascular inflammation, oxidative stress, and neutrophil activation; and (3) Determine if Mg-supplementation attenuates AZT-enhanced myocardial susceptibility to imposed ischemia/reperfusion (I/R) stress ex vivo. We will employ immunohistochemical and pathology techniques to localize inflammatory cyokines and white blood cell infiltrates. Oxidative stress in vivo will be determined biochemically by changes in tissue/blood glutathione status, iron status, and lipid peroxidation products (F2-isoprostanes, conjugated dienes). Changes in tolerance to perfused heart l/R-stress will be determined by free radical production (ESR spin trapping), and alterations in oxidative tissue injury markers and functional recovery. This proposed exploratory effort may reveal a potential usefulness of Mg-supplements as an effective, yet relatively inexpensive adjunct therapy to lessen NRTI-related cardiovascular toxicity.